table

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Version: v1.5.4 Latest Latest
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Published: Sep 19, 2018 License: Apache-2.0 Imports: 17 Imported by: 0

README

BenchmarkRead

$ go test -bench Read$ -count 3

Size of table: 105843444
BenchmarkRead-8   	3	 343846914 ns/op
BenchmarkRead-8   	3	 351790907 ns/op
BenchmarkRead-8   	3	 351762823 ns/op

Size of table is 105,843,444 bytes, which is ~101M.

The rate is ~287M/s which matches our read speed. This is using mmap.

To read a 64M table, this would take ~0.22s, which is negligible.

$ go test -bench BenchmarkReadAndBuild -count 3

BenchmarkReadAndBuild-8   	       1	2341034225 ns/op
BenchmarkReadAndBuild-8   	       1	2346349671 ns/op
BenchmarkReadAndBuild-8   	       1	2364064576 ns/op

The rate is ~43M/s. To build a ~64M table, this would take ~1.5s. Note that this does NOT include the flushing of the table to disk. All we are doing above is to read one table (mmaped) and write one table in memory.

The table building takes 1.5-0.22 ~ 1.3s.

If we are writing out up to 10 tables, this would take 1.5*10 ~ 15s, and ~13s is spent building the tables.

When running populate, building one table in memory tends to take ~1.5s to ~2.5s on my system. Where does this overhead come from? Let's investigate the merging.

Below, we merge 5 tables. The total size remains unchanged at ~101M.

$ go test -bench ReadMerged -count 3
BenchmarkReadMerged-8   	       1	1321190264 ns/op
BenchmarkReadMerged-8   	       1	1296958737 ns/op
BenchmarkReadMerged-8   	       1	1314381178 ns/op

The rate is ~76M/s. To build a 64M table, this would take ~0.84s. The writing takes ~1.3s as we saw above. So in total, we expect around 0.84+1.3 ~ 2.1s. This roughly matches what we observe when running populate. There might be some additional overhead due to the concurrent writes going on, in flushing the table to disk. Also, the tables tend to be slightly bigger than 64M/s.

Documentation

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func IDToFilename

func IDToFilename(id uint64) string

IDToFilename does the inverse of ParseFileID

func NewFilename

func NewFilename(id uint64, dir string) string

NewFilename should be named TableFilepath -- it combines the dir with the ID to make a table filepath.

func ParseFileID

func ParseFileID(name string) (uint64, bool)

ParseFileID reads the file id out of a filename.

Types

type Builder

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

Builder is used in building a table.

func NewTableBuilder

func NewTableBuilder() *Builder

NewTableBuilder makes a new TableBuilder.

func (*Builder) Add

func (b *Builder) Add(key []byte, value y.ValueStruct) error

Add adds a key-value pair to the block. If doNotRestart is true, we will not restart even if b.counter >= restartInterval.

func (*Builder) Close

func (b *Builder) Close()

Close closes the TableBuilder.

func (*Builder) Empty

func (b *Builder) Empty() bool

Empty returns whether it's empty.

func (*Builder) Finish

func (b *Builder) Finish() []byte

Finish finishes the table by appending the index.

func (*Builder) ReachedCapacity

func (b *Builder) ReachedCapacity(cap int64) bool

ReachedCapacity returns true if we... roughly (?) reached capacity?

type ConcatIterator

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

ConcatIterator concatenates the sequences defined by several iterators. (It only works with TableIterators, probably just because it's faster to not be so generic.)

func NewConcatIterator

func NewConcatIterator(tbls []*Table, reversed bool) *ConcatIterator

NewConcatIterator creates a new concatenated iterator

func (*ConcatIterator) Close

func (s *ConcatIterator) Close() error

Close implements y.Interface.

func (*ConcatIterator) Key

func (s *ConcatIterator) Key() []byte

Key implements y.Interface

func (*ConcatIterator) Next

func (s *ConcatIterator) Next()

Next advances our concat iterator.

func (*ConcatIterator) Rewind

func (s *ConcatIterator) Rewind()

Rewind implements y.Interface

func (*ConcatIterator) Seek

func (s *ConcatIterator) Seek(key []byte)

Seek brings us to element >= key if reversed is false. Otherwise, <= key.

func (*ConcatIterator) Valid

func (s *ConcatIterator) Valid() bool

Valid implements y.Interface

func (*ConcatIterator) Value

func (s *ConcatIterator) Value() y.ValueStruct

Value implements y.Interface

type Iterator

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

Iterator is an iterator for a Table.

func (*Iterator) Close

func (itr *Iterator) Close() error

Close closes the iterator (and it must be called).

func (*Iterator) Key

func (itr *Iterator) Key() []byte

Key follows the y.Iterator interface

func (*Iterator) Next

func (itr *Iterator) Next()

Next follows the y.Iterator interface

func (*Iterator) Rewind

func (itr *Iterator) Rewind()

Rewind follows the y.Iterator interface

func (*Iterator) Seek

func (itr *Iterator) Seek(key []byte)

Seek follows the y.Iterator interface

func (*Iterator) Valid

func (itr *Iterator) Valid() bool

Valid follows the y.Iterator interface

func (*Iterator) Value

func (itr *Iterator) Value() (ret y.ValueStruct)

Value follows the y.Iterator interface

type Table

type Table struct {
	sync.Mutex
	// contains filtered or unexported fields
}

Table represents a loaded table file with the info we have about it

func OpenTable

func OpenTable(fd *os.File, loadingMode options.FileLoadingMode) (*Table, error)

OpenTable assumes file has only one table and opens it. Takes ownership of fd upon function entry. Returns a table with one reference count on it (decrementing which may delete the file! -- consider t.Close() instead). The fd has to writeable because we call Truncate on it before deleting.

func (*Table) Biggest

func (t *Table) Biggest() []byte

Biggest is its biggest key, or nil if there are none

func (*Table) Close

func (t *Table) Close() error

Close closes the open table. (Releases resources back to the OS.)

func (*Table) DecrRef

func (t *Table) DecrRef() error

DecrRef decrements the refcount and possibly deletes the table

func (*Table) DoesNotHave

func (t *Table) DoesNotHave(key []byte) bool

DoesNotHave returns true if (but not "only if") the table does not have the key. It does a bloom filter lookup.

func (*Table) Filename

func (t *Table) Filename() string

Filename is NOT the file name. Just kidding, it is.

func (*Table) ID

func (t *Table) ID() uint64

ID is the table's ID number (used to make the file name).

func (*Table) IncrRef

func (t *Table) IncrRef()

IncrRef increments the refcount (having to do with whether the file should be deleted)

func (*Table) NewIterator

func (t *Table) NewIterator(reversed bool) *Iterator

NewIterator returns a new iterator of the Table

func (*Table) Size

func (t *Table) Size() int64

Size is its file size in bytes

func (*Table) Smallest

func (t *Table) Smallest() []byte

Smallest is its smallest key, or nil if there are none

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