nutsdb

README

NutsDB

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NutsDB is a simple, fast, embeddable and persistent key/value store written in pure Go.

It supports fully serializable transactions and many data structures such as list、set、sorted set. All operations happen inside a Tx. Tx represents a transaction, which can be read-only or read-write. Read-only transactions can read values for a given bucket and a given key or iterate over a set of key-value pairs. Read-write transactions can read, update and delete keys from the DB.

Announcement

• v0.11.0 release, see for details: https://github.com/nutsdb/nutsdb/issues/219
• v0.10.0 release, see for details: https://github.com/nutsdb/nutsdb/issues/193
• v0.9.0 release, see for details: https://github.com/nutsdb/nutsdb/issues/167

📢 Note: Starting from v0.9.0, defaultSegmentSize in DefaultOptions has been adjusted from 8MB to 256MB. The original value is the default value, which needs to be manually changed to 8MB, otherwise the original data will not be parsed. The reason for the size adjustment here is that there is a cache for file descriptors starting from v0.9.0 (detail see https://github.com/nutsdb/nutsdb/pull/164 ), so users need to look at the number of fds they use on the server, which can be set manually. If you have any questions, you can open an issue.

Architecture

Welcome contributions to NutsDB.

Table of Contents

• Getting Started
  • Installing
  • Opening a database
  • Options
    • Default Options
  • Transactions
    • Read-write transactions
    • Read-only transactions
    • Managing transactions manually
  • Using buckets
    • Iterate buckets
    • Delete bucket
  • Using key/value pairs
  • Using TTL(Time To Live)
  • Iterating over keys
    • Prefix scans
    • Prefix search scans
    • Range scans
    • Get all
    • Iterator
  • Merge Operation
  • Database backup
  • Using in memory mode
  • Using other data structures
    • List
      • RPush
      • LPush
      • LPop
      • LPeek
      • RPop
      • RPeek
      • LRange
      • LRem
      • LRemByIndex
      • LSet
      • Ltrim
      • LSize
      • LKeys
    • Set
      • SAdd
      • SAreMembers
      • SCard
      • SDiffByOneBucket
      • SDiffByTwoBuckets
      • SHasKey
      • SIsMember
      • SMembers
      • SMoveByOneBucket
      • SMoveByTwoBuckets
      • SPop
      • SRem
      • SUnionByOneBucket
      • SUnionByTwoBuckets
      • SKeys
    • Sorted Set
      • ZAdd
      • ZCard
      • ZCount
      • ZGetByKey
      • ZMembers
      • ZPeekMax
      • ZPeekMin
      • ZPopMax
      • ZPopMin
      • ZRangeByRank
      • ZRangeByScore
      • ZRank
      • ZKeys
    • ZRevRank
      • ZRem
      • ZRemRangeByRank
      • ZScore
  • Comparison with other databases
    • BoltDB
    • LevelDB, RocksDB
    • Badger
  • Benchmarks
  • Caveats & Limitations
  • Contact
  • Contributing
  • Acknowledgements
  • License

Getting Started

Installing

To start using NutsDB, first needs Go installed (version 1.11+ is required). and run go get:

go get -u github.com/xujiajun/nutsdb

Opening a database

To open your database, use the nutsdb.Open() function,with the appropriate options.The Dir , EntryIdxMode and SegmentSize options are must be specified by the client. About options see here for detail.

package main

import (
    "log"

    "github.com/xujiajun/nutsdb"
)

func main() {
    // Open the database located in the /tmp/nutsdb directory.
    // It will be created if it doesn't exist.
    db, err := nutsdb.Open(
        nutsdb.DefaultOptions,
        nutsdb.WithDir("/tmp/nutsdb"),
    )
    if err != nil {
        log.Fatal(err)
    }
    defer db.Close()

    ...
}

Options

• Dir string

Dir represents Open the database located in which dir.

• EntryIdxMode EntryIdxMode

EntryIdxMode represents using which mode to index the entries. EntryIdxMode includes three options: HintKeyValAndRAMIdxMode,HintKeyAndRAMIdxMode and HintBPTSparseIdxMode. HintKeyValAndRAMIdxMode represents ram index (key and value) mode, HintKeyAndRAMIdxMode represents ram index (only key) mode and HintBPTSparseIdxMode represents b+ tree sparse index mode.

• RWMode RWMode

RWMode represents the read and write mode. RWMode includes two options: FileIO and MMap. FileIO represents the read and write mode using standard I/O. And MMap represents the read and write mode using mmap.

• SegmentSize int64

NutsDB will truncate data file if the active file is larger than SegmentSize. Current version default SegmentSize is 8MB,but you can custom it. The defaultSegmentSize becomes 256MB when the version is greater than 0.8.0.

Once set, it cannot be changed. see caveats--limitations for detail.

• NodeNum int64

NodeNum represents the node number.Default NodeNum is 1. NodeNum range [1,1023] .

• SyncEnable bool

SyncEnable represents if call Sync() function. if SyncEnable is false, high write performance but potential data loss likely. if SyncEnable is true, slower but persistent.

• StartFileLoadingMode RWMode

StartFileLoadingMode represents when open a database which RWMode to load files.

Default Options

Recommend to use the DefaultOptions . Unless you know what you're doing.

var DefaultOptions = Options{
    EntryIdxMode:         HintKeyValAndRAMIdxMode,
    SegmentSize:          defaultSegmentSize,
    NodeNum:              1,
    RWMode:               FileIO,
    SyncEnable:           true,
    StartFileLoadingMode: MMap,
}

Transactions

NutsDB allows only one read-write transaction at a time but allows as many read-only transactions as you want at a time. Each transaction has a consistent view of the data as it existed when the transaction started.

When a transaction fails, it will roll back, and revert all changes that occurred to the database during that transaction. If the option SyncEnable is set to true, when a read/write transaction succeeds, all changes are persisted to disk.

Creating transaction from the DB is thread safe.

Read-write transactions

err := db.Update(
    func(tx *nutsdb.Tx) error {
    ...
    return nil
})

Read-only transactions

err := db.View(
    func(tx *nutsdb.Tx) error {
    ...
    return nil
})

Managing transactions manually

The DB.View() and DB.Update() functions are wrappers around the DB.Begin() function. These helper functions will start the transaction, execute a function, and then safely close your transaction if an error is returned. This is the recommended way to use NutsDB transactions.

However, sometimes you may want to manually start and end your transactions. You can use the DB.Begin() function directly but please be sure to close the transaction.

 // Start a write transaction.
tx, err := db.Begin(true)
if err != nil {
    return err
}

bucket := "bucket1"
key := []byte("foo")
val := []byte("bar")

// Use the transaction.
if err = tx.Put(bucket, key, val, nutsdb.Persistent); err != nil {
    // Rollback the transaction.
    tx.Rollback()
} else {
    // Commit the transaction and check for error.
    if err = tx.Commit(); err != nil {
        tx.Rollback()
        return err
    }
}

Using buckets

Buckets are collections of key/value pairs within the database. All keys in a bucket must be unique. Bucket can be interpreted as a table or namespace. So you can store the same key in different bucket.

key := []byte("key001")
val := []byte("val001")

bucket001 := "bucket001"
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        if err := tx.Put(bucket001, key, val, 0); err != nil {
            return err
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

bucket002 := "bucket002"
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        if err := tx.Put(bucket002, key, val, 0); err != nil {
            return err
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

Also, this bucket is related to the data structure you use. Different data index structures that use the same bucket are also different. For example, you define a bucket named bucket_foo, so you need to use the list data structure, use tx.RPush to add data, you must query or retrieve from this bucket_foo data structure, use tx.RPop, tx.LRange, etc. You cannot use tx.Get (same index type as tx.GetAll, tx.Put, tx.Delete, tx.RangeScan, etc.) to read the data in this bucket_foo, because the index structure is different. Other data structures such as Set, Sorted Set are the same.

Iterate buckets

IterateBuckets iterates over all the buckets that match the pattern. IterateBuckets function has three parameters: ds, pattern and function f.

The current version of the Iterate Buckets method supports the following EntryId Modes:

• HintKeyValAndRAMIdxMode：represents ram index (key and value) mode.
• HintKeyAndRAMIdxMode：represents ram index (only key) mode.

The pattern added in version 0.11.0 (represents the pattern to match):

• pattern syntax refer to: filepath.Match

The current version of ds (represents the data structure):

• DataStructureSet
• DataStructureSortedSet
• DataStructureBPTree
• DataStructureList

if err := db.View(
    func(tx *nutsdb.Tx) error {
        return tx.IterateBuckets(nutsdb.DataStructureBPTree, "*", func(bucket string) bool {
            fmt.Println("bucket: ", bucket)
            // true: continue, false: break
            return true
        })
    }); err != nil {
    log.Fatal(err)
}
    

Delete bucket

DeleteBucket represents delete bucket. DeleteBucket function has two parameters: ds(represents the data structure) and bucket.

The current version of the Iterate Buckets method supports the following EntryId Modes:

• HintKeyValAndRAMIdxMode：represents ram index (key and value) mode.
• HintKeyAndRAMIdxMode：represents ram index (only key) mode.

The current version of ds (represents the data structure)：

• DataStructureSet
• DataStructureSortedSet
• DataStructureBPTree
• DataStructureList

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.DeleteBucket(nutsdb.DataStructureBPTree, bucket)
    }); err != nil {
    log.Fatal(err)
}
    

Using key/value pairs

To save a key/value pair to a bucket, use the tx.Put method:

if err := db.Update(
    func(tx *nutsdb.Tx) error {
    key := []byte("name1")
    val := []byte("val1")
    bucket := "bucket1"
    if err := tx.Put(bucket, key, val, 0); err != nil {
        return err
    }
    return nil
}); err != nil {
    log.Fatal(err)
}

This will set the value of the "name1" key to "val1" in the bucket1 bucket.

To update the the value of the "name1" key,we can still use the tx.Put function:

if err := db.Update(
    func(tx *nutsdb.Tx) error {
    key := []byte("name1")
    val := []byte("val1-modify") // Update the value
    bucket := "bucket1"
    if err := tx.Put(bucket, key, val, 0); err != nil {
        return err
    }
    return nil
}); err != nil {
    log.Fatal(err)
}

To retrieve this value, we can use the tx.Get function:

if err := db.View(
func(tx *nutsdb.Tx) error {
    key := []byte("name1")
    bucket := "bucket1"
    if e, err := tx.Get(bucket, key); err != nil {
        return err
    } else {
        fmt.Println(string(e.Value)) // "val1-modify"
    }
    return nil
}); err != nil {
    log.Println(err)
}

Use the tx.Delete() function to delete a key from the bucket.

if err := db.Update(
    func(tx *nutsdb.Tx) error {
    key := []byte("name1")
    bucket := "bucket1"
    if err := tx.Delete(bucket, key); err != nil {
        return err
    }
    return nil
}); err != nil {
    log.Fatal(err)
}

Using TTL(Time To Live)

NusDB supports TTL(Time to Live) for keys, you can use tx.Put function with a ttl parameter.

if err := db.Update(
    func(tx *nutsdb.Tx) error {
    key := []byte("name1")
    val := []byte("val1")
    bucket := "bucket1"
    
    // If set ttl = 0 or Persistent, this key will never expired.
    // Set ttl = 60 , after 60 seconds, this key will expired.
    if err := tx.Put(bucket, key, val, 60); err != nil {
        return err
    }
    return nil
}); err != nil {
    log.Fatal(err)
}

Iterating over keys

NutsDB stores its keys in byte-sorted order within a bucket. This makes sequential iteration over these keys extremely fast.

Prefix scans

To iterate over a key prefix, we can use PrefixScan function, and the parameters offsetNum and limitNum constrain the number of entries returned :

if err := db.View(
    func(tx *nutsdb.Tx) error {
        prefix := []byte("user_")
        bucket := "user_list"
        // Constrain 100 entries returned 
        if entries, _, err := tx.PrefixScan(bucket, prefix, 25, 100); err != nil {
            return err
        } else {
            for _, entry := range entries {
                fmt.Println(string(entry.Key), string(entry.Value))
            }
        }
        return nil
    }); err != nil {
        log.Fatal(err)
}

Prefix search scans

To iterate over a key prefix with search by regular expression on a second part of key without prefix, we can use PrefixSearchScan function, and the parameters offsetNum, limitNum constrain the number of entries returned :

if err := db.View(
    func(tx *nutsdb.Tx) error {
        prefix := []byte("user_")
        reg := "username"
        bucket := "user_list"
        // Constrain 100 entries returned 
        if entries, _, err := tx.PrefixSearchScan(bucket, prefix, reg, 25, 100); err != nil {
            return err
        } else {
            for _, entry := range entries {
                fmt.Println(string(entry.Key), string(entry.Value))
            }
        }
        return nil
    }); err != nil {
        log.Fatal(err)
}

Range scans

To scan over a range, we can use RangeScan function. For example：

if err := db.View(
    func(tx *nutsdb.Tx) error {
        // Assume key from user_0000000 to user_9999999.
        // Query a specific user key range like this.
        start := []byte("user_0010001")
        end := []byte("user_0010010")
        bucket := "user_list"
        if entries, err := tx.RangeScan(bucket, start, end); err != nil {
            return err
        } else {
            for _, entry := range entries {
                fmt.Println(string(entry.Key), string(entry.Value))
            }
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

Get all

To scan all keys and values of the bucket stored, we can use GetAll function. For example:

if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "user_list"
        entries, err := tx.GetAll(bucket)
        if err != nil {
            return err
        }

        for _, entry := range entries {
            fmt.Println(string(entry.Key),string(entry.Value))
        }

        return nil
    }); err != nil {
    log.Println(err)
}

iterator

The option parameter 'Reverse' that determines whether the iterator is forward or Reverse. The current version does not support the iterator for HintBPTSparseIdxMode.

forward iterator

tx, err := db.Begin(false)
iterator := nutsdb.NewIterator(tx, bucket, nutsdb.IteratorOptions{Reverse: false})
i := 0
for i < 10 {
    ok, err := iterator.SetNext()
    fmt.Println("ok, err", ok, err)
    fmt.Println("Key: ", string(iterator.Entry().Key))
    fmt.Println("Value: ", string(iterator.Entry().Value))
    fmt.Println()
    i++
}
err = tx.Commit()
if err != nil {
    panic(err)
}

reverse iterator

tx, err := db.Begin(false)
iterator := nutsdb.NewIterator(tx, bucket, nutsdb.IteratorOptions{Reverse: true})
i := 0
for i < 10 {
    ok, err := iterator.SetNext()
    fmt.Println("ok, err", ok, err)
    fmt.Println("Key: ", string(iterator.Entry().Key))
    fmt.Println("Value: ", string(iterator.Entry().Value))
    fmt.Println()
    i++
}
err = tx.Commit()
if err != nil {
    panic(err)
}
    

Merge Operation

In order to maintain high-performance writing, NutsDB will write multiple copies of the same key. If your service has multiple updates or deletions to the same key, and you want to merge the same key, you can use NutsDB to provide db.Merge()method. This method requires you to write a merge strategy according to the actual situation. Once executed, it will block normal write requests, so it is best to avoid peak periods, such as scheduled execution in the middle of the night.

Of course, if you don't have too many updates or deletes for the same key, it is recommended not to use the Merge() function.

err := db.Merge()
if err != nil {
    ...
}

Notice: the HintBPTSparseIdxMode mode does not support the merge operation of the current version.

Database backup

NutsDB is easy to backup. You can use the db.Backup() function at given dir, call this function from a read-only transaction, and it will perform a hot backup and not block your other database reads and writes.

err = db.Backup(dir)
if err != nil {
   ...
}

NutsDB also provides gzip to compress backups. You can use the db.BackupTarGZ() function.

f, _ := os.Create(path)
defer f.Close()
err = db.BackupTarGZ(f)
if err != nil {
   ...
}
    

Using in memory mode

In-memory mode is supported since nutsdb 0.7.0.

Run memory mode, after restarting the service, the data will be lost.

opts := inmemory.DefaultOptions
db, err := inmemory.Open(opts)
if err != nil {
    ...
}
bucket := "bucket1"
key := []byte("key1")
val := []byte("val1")
err = db.Put(bucket, key, val, 0)
if err != nil {
    ...
}

entry, err := db.Get(bucket, key)
if err != nil {
    ...
}

fmt.Println("entry.Key", string(entry.Key))     // entry.Key key1
fmt.Println("entry.Value", string(entry.Value)) // entry.Value val1

In memory mode, there are some non-memory mode APIs that have not yet been implemented. If you need, you can submit an issue and explain your request.

Using other data structures

The syntax here is modeled after Redis commands

List

RPush

Inserts the values at the tail of the list stored in the bucket at given bucket, key and values.

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "bucketForList"
        key := []byte("myList")
        val := []byte("val1")
        return tx.RPush(bucket, key, val)
    }); err != nil {
    log.Fatal(err)
}

LPush

Inserts the values at the head of the list stored in the bucket at given bucket, key and values.

if err := db.Update(
    func(tx *nutsdb.Tx) error {
            bucket := "bucketForList"
        key := []byte("myList")
        val := []byte("val2")
        return tx.LPush(bucket, key, val)
    }); err != nil {
    log.Fatal(err)
}

LPop

Removes and returns the first element of the list stored in the bucket at given bucket and key.

if err := db.Update(
    func(tx *nutsdb.Tx) error {
            bucket := "bucketForList"
        key := []byte("myList")
        if item, err := tx.LPop(bucket, key); err != nil {
            return err
        } else {
            fmt.Println("LPop item:", string(item))
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

LPeek

Returns the first element of the list stored in the bucket at given bucket and key.

if err := db.View(
    func(tx *nutsdb.Tx) error {
            bucket := "bucketForList"
        key := []byte("myList")
        if item, err := tx.LPeek(bucket, key); err != nil {
            return err
        } else {
            fmt.Println("LPeek item:", string(item)) //val11
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

RPop

Removes and returns the last element of the list stored in the bucket at given bucket and key.

if err := db.Update(
    func(tx *nutsdb.Tx) error {
            bucket := "bucketForList"
        key := []byte("myList")
        if item, err := tx.RPop(bucket, key); err != nil {
            return err
        } else {
            fmt.Println("RPop item:", string(item))
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

RPeek

Returns the last element of the list stored in the bucket at given bucket and key.

if err := db.View(
    func(tx *nutsdb.Tx) error {
            bucket := "bucketForList"
        key := []byte("myList")
        if item, err := tx.RPeek(bucket, key); err != nil {
            return err
        } else {
            fmt.Println("RPeek item:", string(item))
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

LRange

Returns the specified elements of the list stored in the bucket at given bucket,key, start and end. The offsets start and stop are zero-based indexes 0 being the first element of the list (the head of the list), 1 being the next element and so on. Start and end can also be negative numbers indicating offsets from the end of the list, where -1 is the last element of the list, -2 the penultimate element and so on.

if err := db.View(
    func(tx *nutsdb.Tx) error {
            bucket := "bucketForList"
        key := []byte("myList")
        if items, err := tx.LRange(bucket, key, 0, -1); err != nil {
            return err
        } else {
            //fmt.Println(items)
            for _, item := range items {
                fmt.Println(string(item))
            }
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

LRem

Note: This feature can be used starting from v0.6.0

Removes the first count occurrences of elements equal to value from the list stored in the bucket at given bucket,key,count. The count argument influences the operation in the following ways:

• count > 0: Remove elements equal to value moving from head to tail.
• count < 0: Remove elements equal to value moving from tail to head.
• count = 0: Remove all elements equal to value.

if err := db.Update(
    func(tx *nutsdb.Tx) error {
            bucket := "bucketForList"
        key := []byte("myList")
        return tx.LRem(bucket, key, 1, []byte("value11))
    }); err != nil {
    log.Fatal(err)
}

LRemByIndex

Note: This feature can be used starting from v0.10.0

Remove the element at a specified position (single or multiple) from the list

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "bucketForList"
        key := []byte("myList")
        removedNum, err := tx.LRemByIndex(bucket, key, 0, 1)
        fmt.Printf("removed num %d\n", removedNum)
        return err
    }); err != nil {
    log.Fatal(err)
}

LSet

Sets the list element at index to value.

if err := db.Update(
    func(tx *nutsdb.Tx) error {
            bucket := "bucketForList"
        key := []byte("myList")
        if err := tx.LSet(bucket, key, 0, []byte("val11")); err != nil {
            return err
        } else {
            fmt.Println("LSet ok, index 0 item value => val11")
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

Ltrim

Trims an existing list so that it will contain only the specified range of elements specified. The offsets start and stop are zero-based indexes 0 being the first element of the list (the head of the list), 1 being the next element and so on.Start and end can also be negative numbers indicating offsets from the end of the list, where -1 is the last element of the list, -2 the penultimate element and so on.

if err := db.Update(
    func(tx *nutsdb.Tx) error {
            bucket := "bucketForList"
        key := []byte("myList")
        return tx.LTrim(bucket, key, 0, 1)
    }); err != nil {
    log.Fatal(err)
}

LSize

Returns the size of key in the bucket in the bucket at given bucket and key.

if err := db.Update(
    func(tx *nutsdb.Tx) error {
            bucket := "bucketForList"
        key := []byte("myList")
        if size,err := tx.LSize(bucket, key); err != nil {
            return err
        } else {
            fmt.Println("myList size is ",size)
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

LKeys

find all keys of type List matching a given pattern, similar to Redis command: KEYS

Note: pattern matching use filepath.Match, It is different from redis' behavior in some details, such as [.

if err := db.View(
    func(tx *nutsdb.Tx) error {
        var keys []string
        err := tx.LKeys(bucket, "*", func(key string) bool {
            keys = append(keys, key)
            // true: continue, false: break
            return true
        })
        fmt.Printf("keys: %v\n", keys)
        return err
    }); err != nil {
    log.Fatal(err)
}

Set

SAdd

Adds the specified members to the set stored int the bucket at given bucket,key and items.

if err := db.Update(
    func(tx *nutsdb.Tx) error {
            bucket := "bucketForSet"
        key := []byte("mySet")
        return tx.SAdd(bucket, key, []byte("a"), []byte("b"), []byte("c"))
    }); err != nil {
    log.Fatal(err)
}

SAreMembers

Returns if the specified members are the member of the set int the bucket at given bucket,key and items.

if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "bucketForSet"
        key := []byte("mySet")
        if ok, err := tx.SAreMembers(bucket, key, []byte("a"), []byte("b"), []byte("c")); err != nil {
            return err
        } else {
            fmt.Println("SAreMembers:", ok)
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

SCard

Returns the set cardinality (number of elements) of the set stored in the bucket at given bucket and key.

if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "bucketForSet"
        key := []byte("mySet")
        if num, err := tx.SCard(bucket, key); err != nil {
            return err
        } else {
            fmt.Println("SCard:", num)
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

SDiffByOneBucket

Returns the members of the set resulting from the difference between the first set and all the successive sets in one bucket.

key1 := []byte("mySet1")
key2 := []byte("mySet2")
bucket := "bucketForSet"

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket, key1, []byte("a"), []byte("b"), []byte("c"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket, key2, []byte("c"), []byte("d"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if items, err := tx.SDiffByOneBucket(bucket, key1, key2); err != nil {
            return err
        } else {
            fmt.Println("SDiffByOneBucket:", items)
            for _, item := range items {
                fmt.Println("item", string(item))
            }
            //item a
            //item b
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

SDiffByTwoBuckets

Returns the members of the set resulting from the difference between the first set and all the successive sets in two buckets.

bucket1 := "bucket1"
key1 := []byte("mySet1")

bucket2 := "bucket2"
key2 := []byte("mySet2")

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket1, key1, []byte("a"), []byte("b"), []byte("c"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket2, key2, []byte("c"), []byte("d"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if items, err := tx.SDiffByTwoBuckets(bucket1, key1, bucket2, key2); err != nil {
            return err
        } else {
            fmt.Println("SDiffByTwoBuckets:", items)
            for _, item := range items {
                fmt.Println("item", string(item))
            }
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

SHasKey

Returns if the set in the bucket at given bucket and key.

bucket := "bucketForSet"

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if ok, err := tx.SHasKey(bucket, []byte("mySet")); err != nil {
            return err
        } else {
            fmt.Println("SHasKey", ok)
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

SIsMember

Returns if member is a member of the set stored in the bucket at given bucket, key and item.

bucket := "bucketForSet"

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if ok, err := tx.SIsMember(bucket, []byte("mySet"), []byte("a")); err != nil {
            return err
        } else {
            fmt.Println("SIsMember", ok)
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

SMembers

Returns all the members of the set value stored in the bucket at given bucket and key.

bucket := "bucketForSet"

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if items, err := tx.SMembers(bucket, []byte("mySet")); err != nil {
            return err
        } else {
            fmt.Println("SMembers", items)
            for _, item := range items {
                fmt.Println("item", string(item))
            }
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

SMoveByOneBucket

Moves member from the set at source to the set at destination in one bucket.

bucket3 := "bucket3"

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket3, []byte("mySet1"), []byte("a"), []byte("b"), []byte("c"))
    }); err != nil {
    log.Fatal(err)
}
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket3, []byte("mySet2"), []byte("c"), []byte("d"), []byte("e"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        if ok, err := tx.SMoveByOneBucket(bucket3, []byte("mySet1"), []byte("mySet2"), []byte("a")); err != nil {
            return err
        } else {
            fmt.Println("SMoveByOneBucket", ok)
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if items, err := tx.SMembers(bucket3, []byte("mySet1")); err != nil {
            return err
        } else {
            fmt.Println("after SMoveByOneBucket bucket3 mySet1 SMembers", items)
            for _, item := range items {
                fmt.Println("item", string(item))
            }
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if items, err := tx.SMembers(bucket3, []byte("mySet2")); err != nil {
            return err
        } else {
            fmt.Println("after SMoveByOneBucket bucket3 mySet2 SMembers", items)
            for _, item := range items {
                fmt.Println("item", string(item))
            }
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

SMoveByTwoBuckets

Moves member from the set at source to the set at destination in two buckets.

bucket4 := "bucket4"
bucket5 := "bucket5"
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket4, []byte("mySet1"), []byte("a"), []byte("b"), []byte("c"))
    }); err != nil {
    log.Fatal(err)
}
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket5, []byte("mySet2"), []byte("c"), []byte("d"), []byte("e"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        if ok, err := tx.SMoveByTwoBuckets(bucket4, []byte("mySet1"), bucket5, []byte("mySet2"), []byte("a")); err != nil {
            return err
        } else {
            fmt.Println("SMoveByTwoBuckets", ok)
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if items, err := tx.SMembers(bucket4, []byte("mySet1")); err != nil {
            return err
        } else {
            fmt.Println("after SMoveByTwoBuckets bucket4 mySet1 SMembers", items)
            for _, item := range items {
                fmt.Println("item", string(item))
            }
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if items, err := tx.SMembers(bucket5, []byte("mySet2")); err != nil {
            return err
        } else {
            fmt.Println("after SMoveByTwoBuckets bucket5 mySet2 SMembers", items)
            for _, item := range items {
                fmt.Println("item", string(item))
            }
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

SPop

Removes and returns one or more random elements from the set value store in the bucket at given bucket and key.

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        key := []byte("mySet")
        if item, err := tx.SPop(bucket, key); err != nil {
            return err
        } else {
            fmt.Println("SPop item from mySet:", string(item))
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

SRem

Removes the specified members from the set stored in the bucket at given bucket,key and items.

bucket6:="bucket6"
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket6, []byte("mySet"), []byte("a"), []byte("b"), []byte("c"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        if err := tx.SRem(bucket6, []byte("mySet"), []byte("a")); err != nil {
            return err
        } else {
            fmt.Println("SRem ok")
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if items, err := tx.SMembers(bucket6, []byte("mySet")); err != nil {
            return err
        } else {
            fmt.Println("SMembers items:", items)
            for _, item := range items {
                fmt.Println("item:", string(item))
            }
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

SUnionByOneBucket

The members of the set resulting from the union of all the given sets in one bucket.

bucket7 := "bucket1"
key1 := []byte("mySet1")
key2 := []byte("mySet2")

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket7, key1, []byte("a"), []byte("b"), []byte("c"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket7, key2, []byte("c"), []byte("d"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if items, err := tx.SUnionByOneBucket(bucket7, key1, key2); err != nil {
            return err
        } else {
            fmt.Println("SUnionByOneBucket:", items)
            for _, item := range items {
                fmt.Println("item", string(item))
            }
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

SUnionByTwoBuckets

The members of the set resulting from the union of all the given sets in two buckets.

bucket8 := "bucket1"
key1 := []byte("mySet1")

bucket9 := "bucket2"
key2 := []byte("mySet2")

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket8, key1, []byte("a"), []byte("b"), []byte("c"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket9, key2, []byte("c"), []byte("d"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if items, err := tx.SUnionByTwoBuckets(bucket8, key1, bucket9, key2); err != nil {
            return err
        } else {
            fmt.Println("SUnionByTwoBucket:", items)
            for _, item := range items {
                fmt.Println("item", string(item))
            }
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

SKeys

find all keys of type Set matching a given pattern, similar to Redis command: KEYS

Note: pattern matching use filepath.Match, It is different from redis' behavior in some details, such as [.

if err := db.View(
    func(tx *nutsdb.Tx) error {
        var keys []string
        err := tx.SKeys(bucket, "*", func(key string) bool {
            keys = append(keys, key)
            // true: continue, false: break
            return true
        })
        fmt.Printf("keys: %v\n", keys)
        return err
    }); err != nil {
    log.Fatal(err)
}

Sorted Set

ZAdd

Adds the specified member with the specified score and the specified value to the sorted set stored at bucket.

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        return tx.ZAdd(bucket, key, 1, []byte("val1"))
    }); err != nil {
    log.Fatal(err)
}

ZCard

Returns the sorted set cardinality (number of elements) of the sorted set stored at bucket.

if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        if num, err := tx.ZCard(bucket); err != nil {
            return err
        } else {
            fmt.Println("ZCard num", num)
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

ZCount

Returns the number of elements in the sorted set at bucket with a score between min and max and opts.

Opts includes the following parameters:

• Limit int // limit the max nodes to return
• ExcludeStart bool // exclude start value, so it search in interval (start, end] or (start, end)
• ExcludeEnd bool // exclude end value, so it search in interval [start, end) or (start, end)

if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        if num, err := tx.ZCount(bucket, 0, 1, nil); err != nil {
            return err
        } else {
            fmt.Println("ZCount num", num)
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

ZGetByKey

Returns node in the bucket at given bucket and key.

if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key2")
        if node, err := tx.ZGetByKey(bucket, key); err != nil {
            return err
        } else {
            fmt.Println("ZGetByKey key2 val:", string(node.Value))
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

ZMembers

Returns all the members of the set value stored at bucket.

if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        if nodes, err := tx.ZMembers(bucket); err != nil {
            return err
        } else {
            fmt.Println("ZMembers:", nodes)

            for _, node := range nodes {
                fmt.Println("member:", node.Key(), string(node.Value))
            }
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

ZPeekMax

Returns the member with the highest score in the sorted set stored at bucket.

if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        if node, err := tx.ZPeekMax(bucket); err != nil {
            return err
        } else {
            fmt.Println("ZPeekMax:", string(node.Value))
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

ZPeekMin

Returns the member with lowest score in the sorted set stored at bucket.

if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        if node, err := tx.ZPeekMin(bucket); err != nil {
            return err
        } else {
            fmt.Println("ZPeekMin:", string(node.Value))
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

ZPopMax

Removes and returns the member with the highest score in the sorted set stored at bucket.

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        if node, err := tx.ZPopMax(bucket); err != nil {
            return err
        } else {
            fmt.Println("ZPopMax:", string(node.Value)) //val3
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

ZPopMin

Removes and returns the member with the lowest score in the sorted set stored at bucket.

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        if node, err := tx.ZPopMin(bucket); err != nil {
            return err
        } else {
            fmt.Println("ZPopMin:", string(node.Value)) //val1
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

ZRangeByRank

Returns all the elements in the sorted set in one bucket at bucket and key with a rank between start and end (including elements with rank equal to start or end).

// ZAdd add items
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet2"
        key1 := []byte("key1")
        return tx.ZAdd(bucket, key1, 1, []byte("val1"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet2"
        key2 := []byte("key2")
        return tx.ZAdd(bucket, key2, 2, []byte("val2"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet2"
        key3 := []byte("key3")
        return tx.ZAdd(bucket, key3, 3, []byte("val3"))
    }); err != nil {
    log.Fatal(err)
}

// ZRangeByRank
if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet2"
        if nodes, err := tx.ZRangeByRank(bucket, 1, 2); err != nil {
            return err
        } else {
            fmt.Println("ZRangeByRank nodes :", nodes)
            for _, node := range nodes {
                fmt.Println("item:", node.Key(), node.Score())
            }
            
            //item: key1 1
            //item: key2 2
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

ZRangeByScore

Returns all the elements in the sorted set at key with a score between min and max. And the parameter Opts is the same as ZCount's.

// ZAdd
if err := db.Update(
        func(tx *nutsdb.Tx) error {
            bucket := "myZSet3"
            key1 := []byte("key1")
            return tx.ZAdd(bucket, key1, 70, []byte("val1"))
        }); err != nil {
        log.Fatal(err)
    }

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet3"
        key2 := []byte("key2")
        return tx.ZAdd(bucket, key2, 90, []byte("val2"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet3"
        key3 := []byte("key3")
        return tx.ZAdd(bucket, key3, 86, []byte("val3"))
    }); err != nil {
    log.Fatal(err)
}

// ZRangeByScore
if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet3"
        if nodes, err := tx.ZRangeByScore(bucket, 80, 100,nil); err != nil {
            return err
        } else {
            fmt.Println("ZRangeByScore nodes :", nodes)
            for _, node := range nodes {
                fmt.Println("item:", node.Key(), node.Score())
            }
            //item: key3 86
            //item: key2 90
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}   

ZRank

Returns the rank of member in the sorted set stored in the bucket at given bucket and key, with the scores ordered from low to high.

// ZAdd
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet4"
        key1 := []byte("key1")
        return tx.ZAdd(bucket, key1, 70, []byte("val1"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet4"
        key2 := []byte("key2")
        return tx.ZAdd(bucket, key2, 90, []byte("val2"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet4"
        key3 := []byte("key3")
        return tx.ZAdd(bucket, key3, 86, []byte("val3"))
    }); err != nil {
    log.Fatal(err)
}

// ZRank
if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet4"
        key1 := []byte("key1")
        if rank, err := tx.ZRank(bucket, key1); err != nil {
            return err
        } else {
            fmt.Println("key1 ZRank :", rank) // key1 ZRank : 1
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

ZRevRank

Returns the rank of member in the sorted set stored in the bucket at given bucket and key,with the scores ordered from high to low.

// ZAdd
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet8"
        key1 := []byte("key1")
        return tx.ZAdd(bucket, key1, 10, []byte("val1"))
    }); err != nil {
    log.Fatal(err)
}
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet8"
        key2 := []byte("key2")
        return tx.ZAdd(bucket, key2, 20, []byte("val2"))
    }); err != nil {
    log.Fatal(err)
}
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet8"
        key3 := []byte("key3")
        return tx.ZAdd(bucket, key3, 30, []byte("val3"))
    }); err != nil {
    log.Fatal(err)
}

// ZRevRank
if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet8"
        if rank, err := tx.ZRevRank(bucket, []byte("key3")); err != nil {
            return err
        } else {
            fmt.Println("ZRevRank key1 rank:", rank) //ZRevRank key3 rank: 1
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

ZRem

Removes the specified members from the sorted set stored in one bucket at given bucket and key.

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet5"
        key1 := []byte("key1")
        return tx.ZAdd(bucket, key1, 10, []byte("val1"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet5"
        key2 := []byte("key2")
        return tx.ZAdd(bucket, key2, 20, []byte("val2"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet5"
        if nodes,err := tx.ZMembers(bucket); err != nil {
            return err
        } else {
            fmt.Println("before ZRem key1, ZMembers nodes",nodes)
            for _,node:=range nodes {
                fmt.Println("item:",node.Key(),node.Score())
            }
        }
        // before ZRem key1, ZMembers nodes map[key1:0xc00008cfa0 key2:0xc00008d090]
        // item: key1 10
        // item: key2 20
        return nil
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet5"
        if err := tx.ZRem(bucket, "key1"); err != nil {
            return err
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet5"
        if nodes,err := tx.ZMembers(bucket); err != nil {
            return err
        } else {
            fmt.Println("after ZRem key1, ZMembers nodes",nodes)
            for _,node:=range nodes {
                fmt.Println("item:",node.Key(),node.Score())
            }
            // after ZRem key1, ZMembers nodes map[key2:0xc00008d090]
            // item: key2 20
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

ZRemRangeByRank

Removes all elements in the sorted set stored in one bucket at given bucket with rank between start and end. The rank is 1-based integer. Rank 1 means the first node; Rank -1 means the last node.

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet6"
        key1 := []byte("key1")
        return tx.ZAdd(bucket, key1, 10, []byte("val1"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet6"
        key2 := []byte("key2")
        return tx.ZAdd(bucket, key2, 20, []byte("val2"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet6"
        key3 := []byte("key3")
        return tx.ZAdd(bucket, key3, 30, []byte("val2"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet6"
        if nodes,err := tx.ZMembers(bucket); err != nil {
            return err
        } else {
            fmt.Println("before ZRemRangeByRank, ZMembers nodes",nodes)
            for _,node:=range nodes {
                fmt.Println("item:",node.Key(),node.Score())
            }
            // before ZRemRangeByRank, ZMembers nodes map[key3:0xc00008d450 key1:0xc00008d270 key2:0xc00008d360]
            // item: key1 10
            // item: key2 20
            // item: key3 30
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet6"
        if err := tx.ZRemRangeByRank(bucket, 1,2); err != nil {
            return err
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet6"
        if nodes,err := tx.ZMembers(bucket); err != nil {
            return err
        } else {
            fmt.Println("after ZRemRangeByRank, ZMembers nodes",nodes)
            for _,node:=range nodes {
                fmt.Println("item:",node.Key(),node.Score())
            }
            // after ZRemRangeByRank, ZMembers nodes map[key3:0xc00008d450]
            // item: key3 30
            // key1 ZScore 10
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

ZScore

Returns the score of member in the sorted set in the bucket at given bucket and key.

if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet7"
        if score,err := tx.ZScore(bucket, []byte("key1")); err != nil {
            return err
        } else {
            fmt.Println("ZScore key1 score:",score)
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

ZKeys

find all keys of type Sorted Set matching a given pattern, similar to Redis command: KEYS

Note: pattern matching use filepath.Match, It is different from redis' behavior in some details, such as [.

if err := db.View(
    func(tx *nutsdb.Tx) error {
        var keys []string
        err := tx.ZKeys(bucket, "*", func(key string) bool {
            keys = append(keys, key)
            // true: continue, false: break
            return true
        })
        fmt.Printf("keys: %v\n", keys)
        return err
    }); err != nil {
    log.Fatal(err)
}

Comparison with other databases

BoltDB

BoltDB is similar to NutsDB, both use B+tree and support transaction. However, Bolt uses a B+tree internally and only a single file, and NutsDB is based on bitcask model with multiple log files. NutsDB supports TTL and many data structures, but BoltDB does not support them .

LevelDB, RocksDB

LevelDB and RocksDB are based on a log-structured merge-tree (LSM tree).An LSM tree optimizes random writes by using a write ahead log and multi-tiered, sorted files called SSTables. LevelDB does not have transactions. It supports batch writing of key/value pairs and it supports read snapshots but it will not give you the ability to do a compare-and-swap operation safely. NutsDB supports many data structures, but RocksDB does not support them.

Badger

Badger is based in LSM tree with value log. It designed for SSDs. It also supports transaction and TTL. But in my benchmark its write performance is not as good as i thought. In addition, NutsDB supports data structures such as list、set、sorted set, but Badger does not support them.

Benchmarks

Tested kvstore

Selected kvstore which is embedded, persistence and support transactions.

• BadgerDB (master branch with default options)
• BoltDB (master branch with default options)
• NutsDB (master branch with default options or custom options)

Benchmark System:

• Go Version : go1.11.4 darwin/amd64
• OS: Mac OS X 10.13.6
• Architecture: x86_64
• 16 GB 2133 MHz LPDDR3
• CPU: 3.1 GHz Intel Core i7

Benchmark results:

badger 2019/03/11 18:06:05 INFO: All 0 tables opened in 0s
goos: darwin
goarch: amd64
pkg: github.com/xujiajun/kvstore-bench
BenchmarkBadgerDBPutValue64B-8         10000        112382 ns/op        2374 B/op         74 allocs/op
BenchmarkBadgerDBPutValue128B-8        20000         94110 ns/op        2503 B/op         74 allocs/op
BenchmarkBadgerDBPutValue256B-8        20000         93480 ns/op        2759 B/op         74 allocs/op
BenchmarkBadgerDBPutValue512B-8        10000        101407 ns/op        3271 B/op         74 allocs/op
BenchmarkBadgerDBGet-8               1000000          1552 ns/op         416 B/op          9 allocs/op
BenchmarkBoltDBPutValue64B-8           10000        203128 ns/op       21231 B/op         62 allocs/op
BenchmarkBoltDBPutValue128B-8           5000        229568 ns/op       13716 B/op         64 allocs/op
BenchmarkBoltDBPutValue256B-8          10000        196513 ns/op       17974 B/op         64 allocs/op
BenchmarkBoltDBPutValue512B-8          10000        199805 ns/op       17064 B/op         64 allocs/op
BenchmarkBoltDBGet-8                 1000000          1122 ns/op         592 B/op         10 allocs/op
BenchmarkNutsDBPutValue64B-8           30000         53614 ns/op         626 B/op         14 allocs/op
BenchmarkNutsDBPutValue128B-8          30000         51998 ns/op         664 B/op         13 allocs/op
BenchmarkNutsDBPutValue256B-8          30000         53958 ns/op         920 B/op         13 allocs/op
BenchmarkNutsDBPutValue512B-8          30000         55787 ns/op        1432 B/op         13 allocs/op
BenchmarkNutsDBGet-8                 2000000           661 ns/op          88 B/op          3 allocs/op
BenchmarkNutsDBGetByHintKey-8          50000         27255 ns/op         840 B/op         16 allocs/op
PASS
ok      github.com/xujiajun/kvstore-bench   83.856s

Conclusions:

Put(write) Performance:

NutsDB is fastest. NutsDB is 2-5x faster than BoltDB, 0.5-2x faster than BadgerDB. And BadgerDB is 1-3x faster than BoltDB.

Get(read) Performance:

All are fast. And NutsDB is 1x faster than others. And NutsDB reads with HintKey option is much slower than its default option way.

the benchmark code can be found in the gokvstore-bench repo.

Caveats & Limitations

Index mode

From the version v0.3.0, NutsDB supports two modes about entry index: HintKeyValAndRAMIdxMode and HintKeyAndRAMIdxMode. From the version v0.5.0, NutsDB supports HintBPTSparseIdxMode mode.

The default mode use HintKeyValAndRAMIdxMode, entries are indexed base on RAM, so its read/write performance is fast. but can’t handle databases much larger than the available physical RAM. If you set the HintKeyAndRAMIdxMode mode, HintIndex will not cache the value of the entry. Its write performance is also fast. To retrieve a key by seeking to offset relative to the start of the data file, so its read performance more slowly that RAM way, but it can save memory. The mode HintBPTSparseIdxMode is based b+ tree sparse index, this mode saves memory very much (1 billion data only uses about 80MB of memory). And other data structures such as list, set, sorted set only supported with mode HintKeyValAndRAMIdxMode. It cannot switch back and forth between modes because the index structure is different.

NutsDB will truncate data file if the active file is larger than SegmentSize, so the size of an entry can not be set larger than SegmentSize , default SegmentSize is 8MB, you can set it(opt.SegmentSize) as option before DB opening. Once set, it cannot be changed.

Support OS

NutsDB currently works on Mac OS, Linux and Windows.

About merge operation

The HintBPTSparseIdxMode mode does not support the merge operation of the current version.

About transactions

Recommend use the latest version.

Contact

• xujiajun

Contributing

See CONTRIBUTING for details on submitting patches and the contribution workflow.

Acknowledgements

This package is inspired by the following:

• Bitcask-intro
• BoltDB
• BuntDB
• Redis
• Sorted Set

License

The NutsDB is open-sourced software licensed under the Apache 2.0 license.

Documentation

Overview

Package nutsdb implements a simple, fast, embeddable and persistent key/value store written in pure Go. It supports fully serializable transactions. And it also supports data structure such as list、set、sorted set etc.

NutsDB currently works on Mac OS, Linux and Windows.

Usage

NutsDB has the following main types: DB, BPTree, Entry, DataFile And Tx. and NutsDB supports bucket, A bucket is a collection of unique keys that are associated with values.

All operations happen inside a Tx. Tx represents a transaction, which can be read-only or read-write. Read-only transactions can read values for a given key , or iterate over a set of key-value pairs (prefix scanning or range scanning). read-write transactions can also update and delete keys from the DB.

See the examples for more usage details.

Index

• Constants
• Variables
• func ErrBucketAndKey(bucket string, key []byte) error
• func ErrNotFoundKeyInBucket(bucket string, key []byte) error
• func ErrSeparatorForZSetKey() error
• func ErrWhenBuildListIdx(err error) error
• func IsBucketEmpty(err error) bool
• func IsBucketNotFound(err error) bool
• func IsDBClosed(err error) bool
• func IsExpired(ttl uint32, timestamp uint64) bool
• func IsKeyEmpty(err error) bool
• func IsKeyNotFound(err error) bool
• func IsPrefixScan(err error) bool
• func IsPrefixSearchScan(err error) bool
• func MarshalInts(ints []int) ([]byte, error)
• func MatchForRange(pattern, key string, f func(key string) bool) (end bool, err error)
• func SortFID(BPTreeRootIdxGroup []*BPTreeRootIdx, by sortBy)
• func SortedEntryKeys(m map[string]*Entry) (keys []string, es map[string]*Entry)
• func Truncate(path string, capacity int64, f *os.File) error
• func UnmarshalInts(data []byte) ([]int, error)
• type BPTree
  • func NewTree() *BPTree
  • func (t *BPTree) All() (records Records, err error)
  • func (t *BPTree) Find(key []byte) (*Record, error)
  • func (t *BPTree) FindLeaf(key []byte) *Node
  • func (t *BPTree) FindRange(start, end []byte, f func(key []byte, pointer interface{}) bool) (numFound int, keys [][]byte, pointers []interface{})
  • func (t *BPTree) Insert(key []byte, e *Entry, h *Hint, countFlag bool) error
  • func (t *BPTree) PrefixScan(prefix []byte, offsetNum int, limitNum int) (records Records, off int, err error)
  • func (t *BPTree) PrefixSearchScan(prefix []byte, reg string, offsetNum int, limitNum int) (records Records, off int, err error)
  • func (t *BPTree) Range(start, end []byte) (records Records, err error)
  • func (t *BPTree) SetKeyPosMap(keyPosMap map[string]int64)
  • func (t *BPTree) ToBinary(n *Node) (result []byte, err error)
  • func (t *BPTree) WriteNode(n *Node, off int64, syncEnable bool, fd *os.File) (number int, err error)
  • func (t *BPTree) WriteNodes(rwMode RWMode, syncEnable bool, flag int) error
• type BPTreeIdx
• type BPTreeRootIdx
  • func ReadBPTreeRootIdxAt(fd *os.File, off int64) (*BPTreeRootIdx, error)
  • func (bri *BPTreeRootIdx) Encode() []byte
  • func (bri *BPTreeRootIdx) GetCrc(buf []byte) uint32
  • func (bri *BPTreeRootIdx) IsZero() bool
  • func (bri *BPTreeRootIdx) Persistence(path string, offset int64, syncEnable bool) (number int, err error)
  • func (bri *BPTreeRootIdx) Size() int64
• type BPTreeRootIdxWrapper
  • func (bsw BPTreeRootIdxWrapper) Len() int
  • func (bsw BPTreeRootIdxWrapper) Less(i, j int) bool
  • func (bsw BPTreeRootIdxWrapper) Swap(i, j int)
• type BinaryNode
  • func ReadNode(filePath string, address int64) (bn *BinaryNode, err error)
• type BucketMeta
  • func ReadBucketMeta(name string) (bucketMeta *BucketMeta, err error)
  • func (bm *BucketMeta) Encode() []byte
  • func (bm *BucketMeta) GetCrc(buf []byte) uint32
  • func (bm *BucketMeta) Size() int64
• type BucketMetasIdx
• type DB
  • func Open(options Options, ops ...Option) (*DB, error)
  • func (db *DB) Backup(dir string) error
  • func (db *DB) BackupTarGZ(w io.Writer) error
  • func (db *DB) Begin(writable bool) (tx *Tx, err error)
  • func (db *DB) Close() error
  • func (db *DB) Merge() error
  • func (db *DB) Update(fn func(tx *Tx) error) error
  • func (db *DB) View(fn func(tx *Tx) error) error
• type DataFile
  • func NewDataFile(path string, rwManager RWManager) *DataFile
  • func (df *DataFile) Close() (err error)
  • func (df *DataFile) ReadAt(off int) (e *Entry, err error)
  • func (df *DataFile) Release() (err error)
  • func (df *DataFile) Sync() (err error)
  • func (df *DataFile) WriteAt(b []byte, off int64) (n int, err error)
• type Entries
• type Entry
  • func (e *Entry) Encode() []byte
  • func (e *Entry) GetCrc(buf []byte) uint32
  • func (e *Entry) IsZero() bool
  • func (e *Entry) ParsePayload(data []byte) error
  • func (e *Entry) Size() int64
• type EntryIdxMode
• type FdInfo
• type FileIORWManager
  • func (fm *FileIORWManager) Close() (err error)
  • func (fm *FileIORWManager) ReadAt(b []byte, off int64) (n int, err error)
  • func (fm *FileIORWManager) Release() (err error)
  • func (fm *FileIORWManager) Sync() (err error)
  • func (fm *FileIORWManager) WriteAt(b []byte, off int64) (n int, err error)
• type Hint
• type Iterator
  • func NewIterator(tx *Tx, bucket string, options IteratorOptions) *Iterator
  • func (it *Iterator) Entry() *Entry
  • func (it *Iterator) Seek(key []byte) error
  • func (it *Iterator) SetNext() (bool, error)
• type IteratorOptions
• type ListIdx
• type MMapRWManager
  • func (mm *MMapRWManager) Close() (err error)
  • func (mm *MMapRWManager) ReadAt(b []byte, off int64) (n int, err error)
  • func (mm *MMapRWManager) Release() (err error)
  • func (mm *MMapRWManager) Sync() (err error)
  • func (mm *MMapRWManager) WriteAt(b []byte, off int64) (n int, err error)
• type MetaData
• type Node
• type Option
  • func WithCleanFdsCacheThreshold(threshold float64) Option
  • func WithDir(dir string) Option
  • func WithEntryIdxMode(entryIdxMode EntryIdxMode) Option
  • func WithMaxFdNumsInCache(num int) Option
  • func WithNodeNum(num int64) Option
  • func WithRWMode(rwMode RWMode) Option
  • func WithSegmentSize(size int64) Option
  • func WithSyncEnable(enable bool) Option
• type Options
• type RWManager
• type RWMode
• type Record
  • func (r *Record) IsExpired() bool
  • func (r *Record) UpdateRecord(h *Hint, e *Entry) error
• type Records
• type SetIdx
• type SortedSetIdx
• type Tx
  • func (tx *Tx) Commit() error
  • func (tx *Tx) Delete(bucket string, key []byte) error
  • func (tx *Tx) DeleteBucket(ds uint16, bucket string) error
  • func (tx *Tx) FindLeafOnDisk(fID int64, rootOff int64, key, newKey []byte) (bn *BinaryNode, err error)
  • func (tx *Tx) FindOnDisk(fID uint64, rootOff uint64, key, newKey []byte) (entry *Entry, err error)
  • func (tx *Tx) FindTxIDOnDisk(fID, txID uint64) (ok bool, err error)
  • func (tx *Tx) Get(bucket string, key []byte) (e *Entry, err error)
  • func (tx *Tx) GetAll(bucket string) (entries Entries, err error)
  • func (tx *Tx) IterateBuckets(ds uint16, pattern string, f func(key string) bool) error
  • func (tx *Tx) LKeys(bucket, pattern string, f func(key string) bool) error
  • func (tx *Tx) LPeek(bucket string, key []byte) (item []byte, err error)
  • func (tx *Tx) LPop(bucket string, key []byte) (item []byte, err error)
  • func (tx *Tx) LPush(bucket string, key []byte, values ...[]byte) error
  • func (tx *Tx) LRange(bucket string, key []byte, start, end int) (list [][]byte, err error)
  • func (tx *Tx) LRem(bucket string, key []byte, count int, value []byte) (removedNum int, err error)
  • func (tx *Tx) LRemByIndex(bucket string, key []byte, indexes ...int) (removedNum int, err error)
  • func (tx *Tx) LSet(bucket string, key []byte, index int, value []byte) error
  • func (tx *Tx) LSize(bucket string, key []byte) (int, error)
  • func (tx *Tx) LTrim(bucket string, key []byte, start, end int) error
  • func (tx *Tx) PrefixScan(bucket string, prefix []byte, offsetNum int, limitNum int) (es Entries, off int, err error)
  • func (tx *Tx) PrefixSearchScan(bucket string, prefix []byte, reg string, offsetNum int, limitNum int) (es Entries, off int, err error)
  • func (tx *Tx) Put(bucket string, key, value []byte, ttl uint32) error
  • func (tx *Tx) PutWithTimestamp(bucket string, key, value []byte, ttl uint32, timestamp uint64) error
  • func (tx *Tx) RPeek(bucket string, key []byte) (item []byte, err error)
  • func (tx *Tx) RPop(bucket string, key []byte) (item []byte, err error)
  • func (tx *Tx) RPush(bucket string, key []byte, values ...[]byte) error
  • func (tx *Tx) RangeScan(bucket string, start, end []byte) (es Entries, err error)
  • func (tx *Tx) Rollback() error
  • func (tx *Tx) SAdd(bucket string, key []byte, items ...[]byte) error
  • func (tx *Tx) SAreMembers(bucket string, key []byte, items ...[]byte) (bool, error)
  • func (tx *Tx) SCard(bucket string, key []byte) (int, error)
  • func (tx *Tx) SDiffByOneBucket(bucket string, key1, key2 []byte) (list [][]byte, err error)
  • func (tx *Tx) SDiffByTwoBuckets(bucket1 string, key1 []byte, bucket2 string, key2 []byte) (list [][]byte, err error)
  • func (tx *Tx) SHasKey(bucket string, key []byte) (bool, error)
  • func (tx *Tx) SIsMember(bucket string, key, item []byte) (bool, error)
  • func (tx *Tx) SKeys(bucket, pattern string, f func(key string) bool) error
  • func (tx *Tx) SMembers(bucket string, key []byte) (list [][]byte, err error)
  • func (tx *Tx) SMoveByOneBucket(bucket string, key1, key2, item []byte) (bool, error)
  • func (tx *Tx) SMoveByTwoBuckets(bucket1 string, key1 []byte, bucket2 string, key2, item []byte) (bool, error)
  • func (tx *Tx) SPop(bucket string, key []byte) ([]byte, error)
  • func (tx *Tx) SRem(bucket string, key []byte, items ...[]byte) error
  • func (tx *Tx) SUnionByOneBucket(bucket string, key1, key2 []byte) (list [][]byte, err error)
  • func (tx *Tx) SUnionByTwoBuckets(bucket1 string, key1 []byte, bucket2 string, key2 []byte) (list [][]byte, err error)
  • func (tx *Tx) ZAdd(bucket string, key []byte, score float64, val []byte) error
  • func (tx *Tx) ZCard(bucket string) (int, error)
  • func (tx *Tx) ZCount(bucket string, start, end float64, opts *zset.GetByScoreRangeOptions) (int, error)
  • func (tx *Tx) ZGetByKey(bucket string, key []byte) (*zset.SortedSetNode, error)
  • func (tx *Tx) ZKeys(bucket, pattern string, f func(key string) bool) error
  • func (tx *Tx) ZMembers(bucket string) (map[string]*zset.SortedSetNode, error)
  • func (tx *Tx) ZPeekMax(bucket string) (*zset.SortedSetNode, error)
  • func (tx *Tx) ZPeekMin(bucket string) (*zset.SortedSetNode, error)
  • func (tx *Tx) ZPopMax(bucket string) (*zset.SortedSetNode, error)
  • func (tx *Tx) ZPopMin(bucket string) (*zset.SortedSetNode, error)
  • func (tx *Tx) ZRangeByRank(bucket string, start, end int) ([]*zset.SortedSetNode, error)
  • func (tx *Tx) ZRangeByScore(bucket string, start, end float64, opts *zset.GetByScoreRangeOptions) ([]*zset.SortedSetNode, error)
  • func (tx *Tx) ZRank(bucket string, key []byte) (int, error)
  • func (tx *Tx) ZRem(bucket, key string) error
  • func (tx *Tx) ZRemRangeByRank(bucket string, start, end int) error
  • func (tx *Tx) ZRevRank(bucket string, key []byte) (int, error)
  • func (tx *Tx) ZScore(bucket string, key []byte) (float64, error)

Constants

const (

	// DefaultInvalidAddress returns default invalid node address.
	DefaultInvalidAddress = -1

	// RangeScan returns range scanMode flag.
	RangeScan = "RangeScan"

	// PrefixScan returns prefix scanMode flag.
	PrefixScan = "PrefixScan"

	// PrefixSearchScan returns prefix and search scanMode flag.
	PrefixSearchScan = "PrefixSearchScan"

	// CountFlagEnabled returns enabled CountFlag.
	CountFlagEnabled = true

	// CountFlagDisabled returns disabled CountFlag.
	CountFlagDisabled = false

	// BPTIndexSuffix returns b+ tree index suffix.
	BPTIndexSuffix = ".bptidx"

	// BPTRootIndexSuffix returns b+ tree root index suffix.
	BPTRootIndexSuffix = ".bptridx"

	// BPTTxIDIndexSuffix returns b+ tree tx ID index suffix.
	BPTTxIDIndexSuffix = ".bpttxid"

	// BPTRootTxIDIndexSuffix returns b+ tree root tx ID index suffix.
	BPTRootTxIDIndexSuffix = ".bptrtxid"
)

const (
	// BucketMetaHeaderSize returns the header size of the BucketMeta.
	BucketMetaHeaderSize = 12

	// BucketMetaSuffix returns b+ tree index suffix.
	BucketMetaSuffix = ".meta"
)

const (
	// DataSuffix returns the data suffix
	DataSuffix = ".dat"

	// DataEntryHeaderSize returns the entry header size
	DataEntryHeaderSize = 42
)

const (
	// DataDeleteFlag represents the data delete flag
	DataDeleteFlag uint16 = iota

	// DataSetFlag represents the data set flag
	DataSetFlag

	// DataLPushFlag represents the data LPush flag
	DataLPushFlag

	// DataRPushFlag represents the data RPush flag
	DataRPushFlag

	// DataLRemFlag represents the data LRem flag
	DataLRemFlag

	// DataLPopFlag represents the data LPop flag
	DataLPopFlag

	// DataRPopFlag represents the data RPop flag
	DataRPopFlag

	// DataLSetFlag represents the data LSet flag
	DataLSetFlag

	// DataLTrimFlag represents the data LTrim flag
	DataLTrimFlag

	// DataZAddFlag represents the data ZAdd flag
	DataZAddFlag

	// DataZRemFlag represents the data ZRem flag
	DataZRemFlag

	// DataZRemRangeByRankFlag represents the data ZRemRangeByRank flag
	DataZRemRangeByRankFlag

	// DataZPopMaxFlag represents the data ZPopMax flag
	DataZPopMaxFlag

	// DataZPopMinFlag represents the data aZPopMin flag
	DataZPopMinFlag

	// DataSetBucketDeleteFlag represents the delete Set bucket flag
	DataSetBucketDeleteFlag

	// DataSortedSetBucketDeleteFlag represents the delete Sorted Set bucket flag
	DataSortedSetBucketDeleteFlag

	// DataBPTreeBucketDeleteFlag represents the delete BPTree bucket flag
	DataBPTreeBucketDeleteFlag

	// DataListBucketDeleteFlag represents the delete List bucket flag
	DataListBucketDeleteFlag

	// LRemByIndex represents the data LRemByIndex flag
	DataLRemByIndex
)

const (
	// UnCommitted represents the tx unCommitted status
	UnCommitted uint16 = 0

	// Committed represents the tx committed status
	Committed uint16 = 1

	// Persistent represents the data persistent flag
	Persistent uint32 = 0

	// ScanNoLimit represents the data scan no limit flag
	ScanNoLimit int = -1
)

const (
	// DataStructureSet represents the data structure set flag
	DataStructureSet uint16 = iota

	// DataStructureSortedSet represents the data structure sorted set flag
	DataStructureSortedSet

	// DataStructureBPTree represents the data structure b+ tree flag
	DataStructureBPTree

	// DataStructureList represents the data structure list flag
	DataStructureList

	// DataStructureNone represents not the data structure
	DataStructureNone
)

const (
	B = 1

	KB = 1024 * B

	MB = 1024 * KB

	GB = 1024 * MB
)

const BPTreeRootIdxHeaderSize = 28

BPTreeRootIdxHeaderSize returns the header size of the root index.

const (
	DefaultMaxFileNums = 256
)

const SeparatorForListKey = "|"

SeparatorForListKey represents separator for listKey

const SeparatorForZSetKey = "|"

SeparatorForZSetKey represents separator for zSet key.

const (
	TooManyFileOpenErrSuffix = "too many open files"
)

Variables

var (
	// ErrStartKey is returned when Range is called by a error start key.
	ErrStartKey = errors.New("err start key")

	// ErrScansNoResult is returned when Range or prefixScan or prefixSearchScan are called no result to found.
	ErrScansNoResult = errors.New("range scans or prefix or prefix and search scans no result")

	// ErrPrefixSearchScansNoResult is returned when prefixSearchScan is called no result to found.
	ErrPrefixSearchScansNoResult = errors.New("prefix and search scans no result")

	// ErrKeyNotFound is returned when the key is not in the b+ tree.
	ErrKeyNotFound = errors.New("key not found")

	// ErrBadRegexp is returned when bad regular expression given.
	ErrBadRegexp = errors.New("bad regular expression")
)

var (
	// ErrCrcZero is returned when crc is 0
	ErrCrcZero = errors.New("error crc is 0")

	// ErrCrc is returned when crc is error
	ErrCrc = errors.New("crc error")

	// ErrCapacity is returned when capacity is error.
	ErrCapacity = errors.New("capacity error")
)

var (
	// ErrDBClosed is returned when db is closed.
	ErrDBClosed = errors.New("db is closed")

	// ErrBucket is returned when bucket is not in the HintIdx.
	ErrBucket = errors.New("err bucket")

	// ErrEntryIdxModeOpt is returned when set db EntryIdxMode option is wrong.
	ErrEntryIdxModeOpt = errors.New("err EntryIdxMode option set")

	// ErrFn is returned when fn is nil.
	ErrFn = errors.New("err fn")

	// ErrBucketNotFound is returned when looking for bucket that does not exist
	ErrBucketNotFound = errors.New("bucket not found")

	// ErrNotSupportHintBPTSparseIdxMode is returned not support mode `HintBPTSparseIdxMode`
	ErrNotSupportHintBPTSparseIdxMode = errors.New("not support mode `HintBPTSparseIdxMode`")
)

var (
	// ErrUnmappedMemory is returned when a function is called on unmapped memory
	ErrUnmappedMemory = errors.New("unmapped memory")

	// ErrIndexOutOfBound is returned when given offset out of mapped region
	ErrIndexOutOfBound = errors.New("offset out of mapped region")
)

var (
	// ErrKeyAndValSize is returned when given key and value size is too big.
	ErrKeyAndValSize = errors.New("key and value size too big")

	// ErrTxClosed is returned when committing or rolling back a transaction
	// that has already been committed or rolled back.
	ErrTxClosed = errors.New("tx is closed")

	// ErrTxNotWritable is returned when performing a write operation on
	// a read-only transaction.
	ErrTxNotWritable = errors.New("tx not writable")

	// ErrKeyEmpty is returned if an empty key is passed on an update function.
	ErrKeyEmpty = errors.New("key cannot be empty")

	// ErrBucketEmpty is returned if bucket is empty.
	ErrBucketEmpty = errors.New("bucket is empty")

	// ErrRangeScan is returned when range scanning not found the result
	ErrRangeScan = errors.New("range scans not found")

	// ErrPrefixScan is returned when prefix scanning not found the result
	ErrPrefixScan = errors.New("prefix scans not found")

	// ErrPrefixSearchScan is returned when prefix and search scanning not found the result
	ErrPrefixSearchScan = errors.New("prefix and search scans not found")

	// ErrNotFoundKey is returned when key not found int the bucket on an view function.
	ErrNotFoundKey = errors.New("key not found in the bucket")
)

var DefaultOptions = func() Options {
	return Options{
		EntryIdxMode: HintKeyValAndRAMIdxMode,
		SegmentSize:  defaultSegmentSize,
		NodeNum:      1,
		RWMode:       FileIO,
		SyncEnable:   true,
	}
}()

DefaultOptions represents the default options.

var (
	// ErrSeparatorForListKey returns when list key contains the SeparatorForListKey.
	ErrSeparatorForListKey = errors.Errorf("contain separator (%s) for List key", SeparatorForListKey)
)

Functions

func ErrBucketAndKey

func ErrBucketAndKey(bucket string, key []byte) error

ErrBucketAndKey returns when bucket or key not found.

func ErrNotFoundKeyInBucket

func ErrNotFoundKeyInBucket(bucket string, key []byte) error

ErrNotFoundKeyInBucket returns when key not in the bucket.

func ErrSeparatorForZSetKey

func ErrSeparatorForZSetKey() error

ErrSeparatorForZSetKey returns when zSet key contains the SeparatorForZSetKey flag.

func ErrWhenBuildListIdx

func ErrWhenBuildListIdx(err error) error

ErrWhenBuildListIdx returns err when build listIdx

func IsBucketEmpty

func IsBucketEmpty(err error) bool

IsBucketEmpty is true if the bucket is empty.

func IsBucketNotFound

func IsBucketNotFound(err error) bool

IsBucketNotFound is true if the error indicates the bucket is not exists.

func IsDBClosed

func IsDBClosed(err error) bool

IsDBClosed is true if the error indicates the db was closed.

func IsExpired

func IsExpired(ttl uint32, timestamp uint64) bool

IsExpired checks the ttl if expired or not.

func IsKeyEmpty

func IsKeyEmpty(err error) bool

IsKeyEmpty is true if the key is empty.

func IsKeyNotFound

func IsKeyNotFound(err error) bool

IsKeyNotFound is true if the error indicates the key is not found.

func IsPrefixScan

func IsPrefixScan(err error) bool

IsPrefixScan is true if prefix scanning not found the result.

func IsPrefixSearchScan

func IsPrefixSearchScan(err error) bool

IsPrefixSearchScan is true if prefix and search scanning not found the result.

func MarshalInts

func MarshalInts(ints []int) ([]byte, error)

func MatchForRange

func MatchForRange(pattern, key string, f func(key string) bool) (end bool, err error)

func SortFID

func SortFID(BPTreeRootIdxGroup []*BPTreeRootIdx, by sortBy)

SortFID sorts BPTreeRootIdx data.

func SortedEntryKeys

func SortedEntryKeys(m map[string]*Entry) (keys []string, es map[string]*Entry)

SortedEntryKeys returns sorted entries.

func Truncate

func Truncate(path string, capacity int64, f *os.File) error

Truncate changes the size of the file.

func UnmarshalInts

func UnmarshalInts(data []byte) ([]int, error)

Types

type BPTree

type BPTree struct {
	ValidKeyCount int // the number of the key that not expired or deleted
	FirstKey      []byte
	LastKey       []byte
	LastAddress   int64
	Filepath      string
	// contains filtered or unexported fields
}

BPTree records root node and valid key number.

func NewTree

func NewTree() *BPTree

NewTree returns a newly initialized BPTree Object that implements the BPTree.

func (*BPTree) All

func (t *BPTree) All() (records Records, err error)

All returns all records in the b+ tree.

func (*BPTree) Find

func (t *BPTree) Find(key []byte) (*Record, error)

Find retrieves record at the given key.

func (*BPTree) FindLeaf

func (t *BPTree) FindLeaf(key []byte) *Node

FindLeaf returns leaf at the given key.

func (*BPTree) FindRange

func (t *BPTree) FindRange(start, end []byte, f func(key []byte, pointer interface{}) bool) (numFound int, keys [][]byte, pointers []interface{})

FindRange returns numFound,keys and pointers at the given start key and end key.

func (*BPTree) Insert

func (t *BPTree) Insert(key []byte, e *Entry, h *Hint, countFlag bool) error

Insert inserts record to the b+ tree, and if the key exists, update the record and the counter(if countFlag set true,it will start count).

func (*BPTree) PrefixScan

func (t *BPTree) PrefixScan(prefix []byte, offsetNum int, limitNum int) (records Records, off int, err error)

PrefixScan returns records at the given prefix and limitNum. limitNum: limit the number of the scanned records return.

func (*BPTree) PrefixSearchScan

func (t *BPTree) PrefixSearchScan(prefix []byte, reg string, offsetNum int, limitNum int) (records Records, off int, err error)

PrefixSearchScan returns records at the given prefix, match regular expression and limitNum limitNum: limit the number of the scanned records return.

func (*BPTree) Range

func (t *BPTree) Range(start, end []byte) (records Records, err error)

Range returns records at the given start key and end key.

func (*BPTree) SetKeyPosMap

func (t *BPTree) SetKeyPosMap(keyPosMap map[string]int64)

SetKeyPosMap sets the key offset of all entries in the b+ tree.

func (*BPTree) ToBinary

func (t *BPTree) ToBinary(n *Node) (result []byte, err error)

ToBinary represents convert to a binary node.

func (*BPTree) WriteNode

func (t *BPTree) WriteNode(n *Node, off int64, syncEnable bool, fd *os.File) (number int, err error)

WriteNode writes a binary node to the File starting at byte offset off. It returns the number of bytes written and an error, if any. WriteAt returns a non-nil error when n != len(b).

func (*BPTree) WriteNodes

func (t *BPTree) WriteNodes(rwMode RWMode, syncEnable bool, flag int) error

WriteNodes writes all nodes in the b+ tree to the File starting at byte offset off.

type BPTreeIdx

type BPTreeIdx map[string]*BPTree

BPTreeIdx represents the B+ tree index

type BPTreeRootIdx

type BPTreeRootIdx struct {
	// contains filtered or unexported fields
}

BPTreeRootIdx represents the b+ tree root index.

func ReadBPTreeRootIdxAt

func ReadBPTreeRootIdxAt(fd *os.File, off int64) (*BPTreeRootIdx, error)

ReadBPTreeRootIdxAt reads BPTreeRootIdx entry from the File starting at byte offset off.

func (*BPTreeRootIdx) Encode

func (bri *BPTreeRootIdx) Encode() []byte

Encode returns the slice after the BPTreeRootIdx be encoded.

func (*BPTreeRootIdx) GetCrc

func (bri *BPTreeRootIdx) GetCrc(buf []byte) uint32

GetCrc returns the crc at given buf slice.

func (*BPTreeRootIdx) IsZero

func (bri *BPTreeRootIdx) IsZero() bool

IsZero checks if the BPTreeRootIdx entry is zero or not.

func (*BPTreeRootIdx) Persistence

func (bri *BPTreeRootIdx) Persistence(path string, offset int64, syncEnable bool) (number int, err error)

Persistence writes BPTreeRootIdx entry to the File starting at byte offset off.

func (*BPTreeRootIdx) Size

func (bri *BPTreeRootIdx) Size() int64

Size returns the size of the BPTreeRootIdx entry.

type BPTreeRootIdxWrapper

type BPTreeRootIdxWrapper struct {
	BSGroup []*BPTreeRootIdx
	// contains filtered or unexported fields
}

BPTreeRootIdxWrapper records BSGroup and by, in order to sort.

func (BPTreeRootIdxWrapper) Len

func (bsw BPTreeRootIdxWrapper) Len() int

Len is the number of elements in the collection bsw.BSGroup.

func (BPTreeRootIdxWrapper) Less

func (bsw BPTreeRootIdxWrapper) Less(i, j int) bool

Less reports whether the element with index i should sort before the element with index j.

func (BPTreeRootIdxWrapper) Swap

func (bsw BPTreeRootIdxWrapper) Swap(i, j int)

Swap swaps the elements with indexes i and j.

type BinaryNode

type BinaryNode struct {
	// hint offset
	Keys [order - 1]int64

	// the last pointer would point to the previous node
	// the next to last one pointer would point to the next node
	Pointers    [order + 1]int64
	IsLeaf      uint16
	KeysNum     uint16
	Address     int64
	NextAddress int64
}

BinaryNode represents binary node.

func ReadNode

func ReadNode(filePath string, address int64) (bn *BinaryNode, err error)

ReadNode reads a binary node at given Filepath and address.

type BucketMeta

type BucketMeta struct {
	// contains filtered or unexported fields
}

BucketMeta represents the bucket's meta-information.

func ReadBucketMeta

func ReadBucketMeta(name string) (bucketMeta *BucketMeta, err error)

ReadBucketMeta returns bucketMeta at given file path name.

func (*BucketMeta) Encode

func (bm *BucketMeta) Encode() []byte

Encode returns the slice after the BucketMeta be encoded.

func (*BucketMeta) GetCrc

func (bm *BucketMeta) GetCrc(buf []byte) uint32

GetCrc returns the crc at given buf slice.

func (*BucketMeta) Size

func (bm *BucketMeta) Size() int64

Size returns the size of the BucketMeta.

type BucketMetasIdx

type BucketMetasIdx map[string]*BucketMeta

BucketMetasIdx represents the index of the bucket's meta-information

type DB

type DB struct {
	BPTreeIdx            BPTreeIdx // Hint Index
	BPTreeRootIdxes      []*BPTreeRootIdx
	BPTreeKeyEntryPosMap map[string]int64 // key = bucket+key  val = EntryPos

	SetIdx                  SetIdx
	SortedSetIdx            SortedSetIdx
	ListIdx                 ListIdx
	ActiveFile              *DataFile
	ActiveBPTreeIdx         *BPTree
	ActiveCommittedTxIdsIdx *BPTree

	MaxFileID int64

	KeyCount int // total key number ,include expired, deleted, repeated.
	// contains filtered or unexported fields
}

DB represents a collection of buckets that persist on disk.

func Open

func Open(options Options, ops ...Option) (*DB, error)

Open returns a newly initialized DB object with Option.

func (*DB) Backup

func (db *DB) Backup(dir string) error

Backup copies the database to file directory at the given dir.

func (*DB) BackupTarGZ

func (db *DB) BackupTarGZ(w io.Writer) error

BackupTarGZ Backup copy the database to writer.

func (*DB) Begin

func (db *DB) Begin(writable bool) (tx *Tx, err error)

Begin opens a new transaction. Multiple read-only transactions can be opened at the same time but there can only be one read/write transaction at a time. Attempting to open a read/write transactions while another one is in progress will result in blocking until the current read/write transaction is completed. All transactions must be closed by calling Commit() or Rollback() when done.

func (*DB) Close

func (db *DB) Close() error

Close releases all db resources.

func (*DB) Merge

func (db *DB) Merge() error

Merge removes dirty data and reduce data redundancy,following these steps:

1. Filter delete or expired entry.

2. Write entry to activeFile if the key not exist，if exist miss this write operation.

3. Filter the entry which is committed.

4. At last remove the merged files.

Caveat: Merge is Called means starting multiple write transactions, and it will affect the other write request. so execute it at the appropriate time.

func (*DB) Update

func (db *DB) Update(fn func(tx *Tx) error) error

Update executes a function within a managed read/write transaction.

func (*DB) View

func (db *DB) View(fn func(tx *Tx) error) error

View executes a function within a managed read-only transaction.

type DataFile

type DataFile struct {
	ActualSize int64
	// contains filtered or unexported fields
}

DataFile records about data file information.

func NewDataFile

func NewDataFile(path string, rwManager RWManager) *DataFile

NewDataFile will return a new DataFile Object.

func (*DataFile) Close

func (df *DataFile) Close() (err error)

Close closes the RWManager. If RWManager is FileRWManager represents closes the File, rendering it unusable for I/O. If RWManager is a MMapRWManager represents Unmap deletes the memory mapped region, flushes any remaining changes.

func (*DataFile) ReadAt

func (df *DataFile) ReadAt(off int) (e *Entry, err error)

ReadAt returns entry at the given off(offset).

func (*DataFile) Release

func (df *DataFile) Release() (err error)

func (*DataFile) Sync

func (df *DataFile) Sync() (err error)

Sync commits the current contents of the file to stable storage. Typically, this means flushing the file system's in-memory copy of recently written data to disk.

func (*DataFile) WriteAt

func (df *DataFile) WriteAt(b []byte, off int64) (n int, err error)

WriteAt copies data to mapped region from the b slice starting at given off and returns number of bytes copied to the mapped region.

type Entries

type Entries []*Entry

Entries represents entries

type Entry

type Entry struct {
	Key   []byte
	Value []byte
	Meta  *MetaData
	// contains filtered or unexported fields
}

Entry represents the data item.

func (*Entry) Encode

func (e *Entry) Encode() []byte

Encode returns the slice after the entry be encoded.

the entry stored format:
|----------------------------------------------------------------------------------------------------------------|
|  crc  | timestamp | ksz | valueSize | flag  | TTL  |bucketSize| status | ds   | txId |  bucket |  key  | value |
|----------------------------------------------------------------------------------------------------------------|
| uint32| uint64  |uint32 |  uint32 | uint16  | uint32| uint32 | uint16 | uint16 |uint64 |[]byte|[]byte | []byte |
|----------------------------------------------------------------------------------------------------------------|

func (*Entry) GetCrc

func (e *Entry) GetCrc(buf []byte) uint32

GetCrc returns the crc at given buf slice.

func (*Entry) IsZero

func (e *Entry) IsZero() bool

IsZero checks if the entry is zero or not.

func (*Entry) ParsePayload

func (e *Entry) ParsePayload(data []byte) error

ParsePayload means this function will parse a byte array to bucket, key, size of an entry

func (*Entry) Size

func (e *Entry) Size() int64

Size returns the size of the entry.

type EntryIdxMode

type EntryIdxMode int

EntryIdxMode represents entry index mode.

const (
	// HintKeyValAndRAMIdxMode represents ram index (key and value) mode.
	HintKeyValAndRAMIdxMode EntryIdxMode = iota

	// HintKeyAndRAMIdxMode represents ram index (only key) mode.
	HintKeyAndRAMIdxMode

	// HintBPTSparseIdxMode represents b+ tree sparse index mode.
	HintBPTSparseIdxMode
)

type FdInfo

type FdInfo struct {
	// contains filtered or unexported fields
}

FdInfo holds base fd info

type FileIORWManager

type FileIORWManager struct {
	// contains filtered or unexported fields
}

FileIORWManager represents the RWManager which using standard I/O.

func (*FileIORWManager) Close

func (fm *FileIORWManager) Close() (err error)

Close will remove the cache in the fdm of the specified path, and call the close method of the os of the file

func (*FileIORWManager) ReadAt

func (fm *FileIORWManager) ReadAt(b []byte, off int64) (n int, err error)

ReadAt reads len(b) bytes from the File starting at byte offset off. `ReadAt` is a wrapper of the *File.ReadAt.

func (*FileIORWManager) Release

func (fm *FileIORWManager) Release() (err error)

Release is a wrapper around the reduceUsing method

func (*FileIORWManager) Sync

func (fm *FileIORWManager) Sync() (err error)

Sync commits the current contents of the file to stable storage. Typically, this means flushing the file system's in-memory copy of recently written data to disk. `Sync` is a wrapper of the *File.Sync.

func (*FileIORWManager) WriteAt

func (fm *FileIORWManager) WriteAt(b []byte, off int64) (n int, err error)

WriteAt writes len(b) bytes to the File starting at byte offset off. `WriteAt` is a wrapper of the *File.WriteAt.

type Hint

type Hint struct {
	Key     []byte
	FileID  int64
	Meta    *MetaData
	DataPos uint64
}

Hint represents the index of the key

type Iterator

type Iterator struct {
	// contains filtered or unexported fields
}

func NewIterator

func NewIterator(tx *Tx, bucket string, options IteratorOptions) *Iterator

func (*Iterator) Entry

func (it *Iterator) Entry() *Entry

Entry would return the current Entry item after calling SetNext

func (*Iterator) Seek

func (it *Iterator) Seek(key []byte) error

Seek would seek to the key, If the key is not available it would seek to the first smallest greater key than the input key.

func (*Iterator) SetNext

func (it *Iterator) SetNext() (bool, error)

SetNext would set the next Entry item, and would return (true, nil) if the next item is available Otherwise if the next item is not available it would return (false, nil) If it faces error it would return (false, err)

type IteratorOptions

type IteratorOptions struct {
	Reverse bool
}

type ListIdx

type ListIdx map[string]*list.List

ListIdx represents the list index

type MMapRWManager

type MMapRWManager struct {
	// contains filtered or unexported fields
}

MMapRWManager represents the RWManager which using mmap.

func (*MMapRWManager) Close

func (mm *MMapRWManager) Close() (err error)

Close will remove the cache in the fdm of the specified path, and call the close method of the os of the file

func (*MMapRWManager) ReadAt

func (mm *MMapRWManager) ReadAt(b []byte, off int64) (n int, err error)

ReadAt copies data to b slice from mapped region starting at given off and returns number of bytes copied to the b slice.

func (*MMapRWManager) Release

func (mm *MMapRWManager) Release() (err error)

Release deletes the memory mapped region, flushes any remaining changes

func (*MMapRWManager) Sync

func (mm *MMapRWManager) Sync() (err error)

Sync synchronizes the mapping's contents to the file's contents on disk.

func (*MMapRWManager) WriteAt

func (mm *MMapRWManager) WriteAt(b []byte, off int64) (n int, err error)

WriteAt copies data to mapped region from the b slice starting at given off and returns number of bytes copied to the mapped region.

type MetaData

type MetaData struct {
	KeySize    uint32
	ValueSize  uint32
	Timestamp  uint64
	TTL        uint32
	Flag       uint16 // delete / set
	Bucket     []byte
	BucketSize uint32
	TxID       uint64
	Status     uint16 // committed / uncommitted
	Ds         uint16 // data structure
}

MetaData represents the meta information of the data item.

type Node

type Node struct {
	Keys [][]byte

	KeysNum int
	Next    *Node
	Address int64
	// contains filtered or unexported fields
}

Node records keys and pointers and parent node.

type Option

type Option func(*Options)

func WithCleanFdsCacheThreshold

func WithCleanFdsCacheThreshold(threshold float64) Option

func WithDir

func WithDir(dir string) Option

func WithEntryIdxMode

func WithEntryIdxMode(entryIdxMode EntryIdxMode) Option

func WithMaxFdNumsInCache

func WithMaxFdNumsInCache(num int) Option

func WithNodeNum

func WithNodeNum(num int64) Option

func WithRWMode

func WithRWMode(rwMode RWMode) Option

func WithSegmentSize

func WithSegmentSize(size int64) Option

func WithSyncEnable

func WithSyncEnable(enable bool) Option

type Options

type Options struct {
	// Dir represents Open the database located in which dir.
	Dir string

	// EntryIdxMode represents using which mode to index the entries.
	EntryIdxMode EntryIdxMode

	// RWMode represents the read and write mode.
	// RWMode includes two options: FileIO and MMap.
	// FileIO represents the read and write mode using standard I/O.
	// MMap represents the read and write mode using mmap.
	RWMode      RWMode
	SegmentSize int64

	// NodeNum represents the node number.
	// Default NodeNum is 1. NodeNum range [1,1023].
	NodeNum int64

	// SyncEnable represents if call Sync() function.
	// if SyncEnable is false, high write performance but potential data loss likely.
	// if SyncEnable is true, slower but persistent.
	SyncEnable bool

	// MaxFdNumsInCache represents the max numbers of fd in cache.
	MaxFdNumsInCache int

	// CleanFdsCacheThreshold represents the maximum threshold for recycling fd, it should be between 0 and 1.
	CleanFdsCacheThreshold float64

	// BufferSizeOfRecovery represents the buffer size of recoveryReader buffer Size
	BufferSizeOfRecovery int
}

Options records params for creating DB object.

type RWManager

type RWManager interface {
	WriteAt(b []byte, off int64) (n int, err error)
	ReadAt(b []byte, off int64) (n int, err error)
	Sync() (err error)
	Release() (err error)
	Close() (err error)
}

RWManager represents an interface to a RWManager.

type RWMode

type RWMode int

RWMode represents the read and write mode.

const (
	// FileIO represents the read and write mode using standard I/O.
	FileIO RWMode = iota

	// MMap represents the read and write mode using mmap.
	MMap
)

type Record

type Record struct {
	H *Hint
	E *Entry
}

Record records entry and hint.

func (*Record) IsExpired

func (r *Record) IsExpired() bool

IsExpired returns the record if expired or not.

func (*Record) UpdateRecord

func (r *Record) UpdateRecord(h *Hint, e *Entry) error

UpdateRecord updates the record.

type Records

type Records []*Record

Records records multi-records as result when is called Range or PrefixScan.

type SetIdx

type SetIdx map[string]*set.Set

SetIdx represents the set index

type SortedSetIdx

type SortedSetIdx map[string]*zset.SortedSet

SortedSetIdx represents the sorted set index

type Tx

type Tx struct {
	ReservedStoreTxIDIdxes map[int64]*BPTree
	// contains filtered or unexported fields
}

Tx represents a transaction.

func (*Tx) Commit

func (tx *Tx) Commit() error

Commit commits the transaction, following these steps:

1. check the length of pendingWrites.If there are no writes, return immediately.

2. check if the ActiveFile has not enough space to store entry. if not, call rotateActiveFile function.

3. write pendingWrites to disk, if a non-nil error,return the error.

4. build Hint index.

5. Unlock the database and clear the db field.

func (*Tx) Delete

func (tx *Tx) Delete(bucket string, key []byte) error

Delete removes a key from the bucket at given bucket and key.

func (*Tx) DeleteBucket

func (tx *Tx) DeleteBucket(ds uint16, bucket string) error

DeleteBucket delete bucket depends on ds (represents the data structure)

func (*Tx) FindLeafOnDisk

func (tx *Tx) FindLeafOnDisk(fID int64, rootOff int64, key, newKey []byte) (bn *BinaryNode, err error)

FindLeafOnDisk returns binary leaf node on disk at given fId, rootOff and key.

func (*Tx) FindOnDisk

func (tx *Tx) FindOnDisk(fID uint64, rootOff uint64, key, newKey []byte) (entry *Entry, err error)

FindOnDisk returns entry on disk at given fID, rootOff and key.

func (*Tx) FindTxIDOnDisk

func (tx *Tx) FindTxIDOnDisk(fID, txID uint64) (ok bool, err error)

FindTxIDOnDisk returns if txId on disk at given fid and txID.

func (*Tx) Get

func (tx *Tx) Get(bucket string, key []byte) (e *Entry, err error)

Get retrieves the value for a key in the bucket. The returned value is only valid for the life of the transaction.

func (*Tx) GetAll

func (tx *Tx) GetAll(bucket string) (entries Entries, err error)

GetAll returns all keys and values of the bucket stored at given bucket.

func (*Tx) IterateBuckets

func (tx *Tx) IterateBuckets(ds uint16, pattern string, f func(key string) bool) error

IterateBuckets iterate over all the bucket depends on ds (represents the data structure)

func (*Tx) LKeys

func (tx *Tx) LKeys(bucket, pattern string, f func(key string) bool) error

LKeys find all keys matching a given pattern

func (*Tx) LPeek

func (tx *Tx) LPeek(bucket string, key []byte) (item []byte, err error)

LPeek returns the first element of the list stored in the bucket at given bucket and key.

func (*Tx) LPop

func (tx *Tx) LPop(bucket string, key []byte) (item []byte, err error)

LPop removes and returns the first element of the list stored in the bucket at given bucket and key.

func (*Tx) LPush

func (tx *Tx) LPush(bucket string, key []byte, values ...[]byte) error

LPush inserts the values at the head of the list stored in the bucket at given bucket,key and values.

func (*Tx) LRange

func (tx *Tx) LRange(bucket string, key []byte, start, end int) (list [][]byte, err error)

LRange returns the specified elements of the list stored in the bucket at given bucket,key, start and end. The offsets start and stop are zero-based indexes 0 being the first element of the list (the head of the list), 1 being the next element and so on. Start and end can also be negative numbers indicating offsets from the end of the list, where -1 is the last element of the list, -2 the penultimate element and so on.

func (*Tx) LRem

func (tx *Tx) LRem(bucket string, key []byte, count int, value []byte) (removedNum int, err error)

LRem removes the first count occurrences of elements equal to value from the list stored in the bucket at given bucket,key,count. The count argument influences the operation in the following ways: count > 0: Remove elements equal to value moving from head to tail. count < 0: Remove elements equal to value moving from tail to head. count = 0: Remove all elements equal to value.

func (*Tx) LRemByIndex

func (tx *Tx) LRemByIndex(bucket string, key []byte, indexes ...int) (removedNum int, err error)

LRemByIndex remove the list element at specified index

func (*Tx) LSet

func (tx *Tx) LSet(bucket string, key []byte, index int, value []byte) error

LSet sets the list element at index to value.

func (*Tx) LSize

func (tx *Tx) LSize(bucket string, key []byte) (int, error)

LSize returns the size of key in the bucket in the bucket at given bucket and key.

func (*Tx) LTrim

func (tx *Tx) LTrim(bucket string, key []byte, start, end int) error

LTrim trims an existing list so that it will contain only the specified range of elements specified. the offsets start and stop are zero-based indexes 0 being the first element of the list (the head of the list), 1 being the next element and so on. start and end can also be negative numbers indicating offsets from the end of the list, where -1 is the last element of the list, -2 the penultimate element and so on.

func (*Tx) PrefixScan

func (tx *Tx) PrefixScan(bucket string, prefix []byte, offsetNum int, limitNum int) (es Entries, off int, err error)

PrefixScan iterates over a key prefix at given bucket, prefix and limitNum. LimitNum will limit the number of entries return.

func (*Tx) PrefixSearchScan

func (tx *Tx) PrefixSearchScan(bucket string, prefix []byte, reg string, offsetNum int, limitNum int) (es Entries, off int, err error)

PrefixSearchScan iterates over a key prefix at given bucket, prefix, match regular expression and limitNum. LimitNum will limit the number of entries return.

func (*Tx) Put

func (tx *Tx) Put(bucket string, key, value []byte, ttl uint32) error

Put sets the value for a key in the bucket. a wrapper of the function put.

func (*Tx) PutWithTimestamp

func (tx *Tx) PutWithTimestamp(bucket string, key, value []byte, ttl uint32, timestamp uint64) error

func (*Tx) RPeek

func (tx *Tx) RPeek(bucket string, key []byte) (item []byte, err error)

RPeek returns the last element of the list stored in the bucket at given bucket and key.

func (*Tx) RPop

func (tx *Tx) RPop(bucket string, key []byte) (item []byte, err error)

RPop removes and returns the last element of the list stored in the bucket at given bucket and key.

func (*Tx) RPush

func (tx *Tx) RPush(bucket string, key []byte, values ...[]byte) error

RPush inserts the values at the tail of the list stored in the bucket at given bucket,key and values.

func (*Tx) RangeScan

func (tx *Tx) RangeScan(bucket string, start, end []byte) (es Entries, err error)

RangeScan query a range at given bucket, start and end slice.

func (*Tx) Rollback

func (tx *Tx) Rollback() error

Rollback closes the transaction.

func (*Tx) SAdd

func (tx *Tx) SAdd(bucket string, key []byte, items ...[]byte) error

SAdd adds the specified members to the set stored int the bucket at given bucket,key and items.

func (*Tx) SAreMembers

func (tx *Tx) SAreMembers(bucket string, key []byte, items ...[]byte) (bool, error)

SAreMembers returns if the specified members are the member of the set int the bucket at given bucket,key and items.

func (*Tx) SCard

func (tx *Tx) SCard(bucket string, key []byte) (int, error)

SCard returns the set cardinality (number of elements) of the set stored in the bucket at given bucket and key.

func (*Tx) SDiffByOneBucket

func (tx *Tx) SDiffByOneBucket(bucket string, key1, key2 []byte) (list [][]byte, err error)

SDiffByOneBucket returns the members of the set resulting from the difference between the first set and all the successive sets in one bucket.

func (*Tx) SDiffByTwoBuckets

func (tx *Tx) SDiffByTwoBuckets(bucket1 string, key1 []byte, bucket2 string, key2 []byte) (list [][]byte, err error)

SDiffByTwoBuckets returns the members of the set resulting from the difference between the first set and all the successive sets in two buckets.

func (*Tx) SHasKey

func (tx *Tx) SHasKey(bucket string, key []byte) (bool, error)

SHasKey returns if the set in the bucket at given bucket and key.

func (*Tx) SIsMember

func (tx *Tx) SIsMember(bucket string, key, item []byte) (bool, error)

SIsMember returns if member is a member of the set stored int the bucket at given bucket,key and item.

func (*Tx) SKeys

func (tx *Tx) SKeys(bucket, pattern string, f func(key string) bool) error

SKeys find all keys matching a given pattern

func (*Tx) SMembers

func (tx *Tx) SMembers(bucket string, key []byte) (list [][]byte, err error)

SMembers returns all the members of the set value stored int the bucket at given bucket and key.

func (*Tx) SMoveByOneBucket

func (tx *Tx) SMoveByOneBucket(bucket string, key1, key2, item []byte) (bool, error)

SMoveByOneBucket moves member from the set at source to the set at destination in one bucket.

func (*Tx) SMoveByTwoBuckets

func (tx *Tx) SMoveByTwoBuckets(bucket1 string, key1 []byte, bucket2 string, key2, item []byte) (bool, error)

SMoveByTwoBuckets moves member from the set at source to the set at destination in two buckets.

func (*Tx) SPop

func (tx *Tx) SPop(bucket string, key []byte) ([]byte, error)

SPop removes and returns one or more random elements from the set value store in the bucket at given bucket and key.

func (*Tx) SRem

func (tx *Tx) SRem(bucket string, key []byte, items ...[]byte) error

SRem removes the specified members from the set stored int the bucket at given bucket,key and items.

func (*Tx) SUnionByOneBucket

func (tx *Tx) SUnionByOneBucket(bucket string, key1, key2 []byte) (list [][]byte, err error)

SUnionByOneBucket the members of the set resulting from the union of all the given sets in one bucket.

func (*Tx) SUnionByTwoBuckets

func (tx *Tx) SUnionByTwoBuckets(bucket1 string, key1 []byte, bucket2 string, key2 []byte) (list [][]byte, err error)

SUnionByTwoBuckets the members of the set resulting from the union of all the given sets in two buckets.

func (*Tx) ZAdd

func (tx *Tx) ZAdd(bucket string, key []byte, score float64, val []byte) error

ZAdd adds the specified member key with the specified score and specified val to the sorted set stored at bucket.

func (*Tx) ZCard

func (tx *Tx) ZCard(bucket string) (int, error)

ZCard returns the sorted set cardinality (number of elements) of the sorted set stored at bucket.

func (*Tx) ZCount

func (tx *Tx) ZCount(bucket string, start, end float64, opts *zset.GetByScoreRangeOptions) (int, error)

ZCount returns the number of elements in the sorted set at bucket with a score between min and max and opts. opts includes the following parameters: Limit int // limit the max nodes to return ExcludeStart bool // exclude start value, so it search in interval (start, end] or (start, end) ExcludeEnd bool // exclude end value, so it search in interval [start, end) or (start, end)

func (*Tx) ZGetByKey

func (tx *Tx) ZGetByKey(bucket string, key []byte) (*zset.SortedSetNode, error)

ZGetByKey returns node in the bucket at given bucket and key.

func (*Tx) ZKeys

func (tx *Tx) ZKeys(bucket, pattern string, f func(key string) bool) error

ZKeys find all keys matching a given pattern

func (*Tx) ZMembers

func (tx *Tx) ZMembers(bucket string) (map[string]*zset.SortedSetNode, error)

ZMembers returns all the members of the set value stored at bucket.

func (*Tx) ZPeekMax

func (tx *Tx) ZPeekMax(bucket string) (*zset.SortedSetNode, error)

ZPeekMax returns the member with the highest score in the sorted set stored at bucket.

func (*Tx) ZPeekMin

func (tx *Tx) ZPeekMin(bucket string) (*zset.SortedSetNode, error)

ZPeekMin returns the member with the lowest score in the sorted set stored at bucket.

func (*Tx) ZPopMax

func (tx *Tx) ZPopMax(bucket string) (*zset.SortedSetNode, error)

ZPopMax removes and returns the member with the highest score in the sorted set stored at bucket.

func (*Tx) ZPopMin

func (tx *Tx) ZPopMin(bucket string) (*zset.SortedSetNode, error)

ZPopMin removes and returns the member with the lowest score in the sorted set stored at bucket.

func (*Tx) ZRangeByRank

func (tx *Tx) ZRangeByRank(bucket string, start, end int) ([]*zset.SortedSetNode, error)

ZRangeByRank returns all the elements in the sorted set in one bucket and key with a rank between start and end (including elements with rank equal to start or end).

func (*Tx) ZRangeByScore

func (tx *Tx) ZRangeByScore(bucket string, start, end float64, opts *zset.GetByScoreRangeOptions) ([]*zset.SortedSetNode, error)

ZRangeByScore returns all the elements in the sorted set at bucket with a score between min and max.

func (*Tx) ZRank

func (tx *Tx) ZRank(bucket string, key []byte) (int, error)

ZRank returns the rank of member in the sorted set stored in the bucket at given bucket and key, with the scores ordered from low to high.

func (*Tx) ZRem

func (tx *Tx) ZRem(bucket, key string) error

ZRem removes the specified members from the sorted set stored in one bucket at given bucket and key.

func (*Tx) ZRemRangeByRank

func (tx *Tx) ZRemRangeByRank(bucket string, start, end int) error

ZRemRangeByRank removes all elements in the sorted set stored in one bucket at given bucket with rank between start and end. the rank is 1-based integer. Rank 1 means the first node; Rank -1 means the last node.

func (*Tx) ZRevRank

func (tx *Tx) ZRevRank(bucket string, key []byte) (int, error)

ZRevRank returns the rank of member in the sorted set stored in the bucket at given bucket and key, with the scores ordered from high to low.

func (*Tx) ZScore

func (tx *Tx) ZScore(bucket string, key []byte) (float64, error)

ZScore returns the score of member in the sorted set in the bucket at given bucket and key.