db

Documentation

Index

• Variables
• type DB
• type Item
• type Iterator
• type Txn

Variables

var (
	// ErrKeyNotFound is returned when key isn't found on a txn.Get.
	ErrKeyNotFound = errors.New("Key not found")
)

Types

type DB

type DB interface {
	// NewTransactionAt follows the same logic as DB.NewTransaction(), but uses the
	// provided read timestamp.
	//
	// This is only useful for databases built on top of Badger (like Dgraph), and
	// can be ignored by most users.
	NewTransactionAt(readTs uint64, update bool) Txn
	// SetDiscardTs sets a timestamp at or below which, any invalid or deleted
	// versions can be discarded from the LSM tree, and thence from the value log to
	// reclaim disk space. Can only be used with managed transactions.
	SetDiscardTs(ts uint64)
	Close() error
}

type Item

type Item interface {
	// KeyCopy returns a copy of the key of the item, writing it to dst slice.
	// If nil is passed, or capacity of dst isn't sufficient, a new slice would be allocated and
	// returned.
	KeyCopy(dst []byte) []byte

	// ValueCopy returns a copy of the value of the item from the value log, writing it to dst slice.
	// If nil is passed, or capacity of dst isn't sufficient, a new slice would be allocated and
	// returned. Tip: It might make sense to reuse the returned slice as dst argument for the next call.
	//
	// This function is useful in long running iterate/update transactions to avoid a write deadlock.
	// See Github issue: https://github.com/dgraph-io/badger/issues/315
	ValueCopy(dst []byte) ([]byte, error)
}

type Iterator

type Iterator interface {
	Item() Item
	Valid() bool
	ValidForPrefix(b []byte) bool
	Close()
	Next()
	Seek(key []byte)
}

type Txn

type Txn interface {
	// CommitAt commits the transaction, following the same logic as Commit(), but
	// at the given commit timestamp. This will panic if not used with managed transactions.
	//
	// This is only useful for databases built on top of Badger (like Dgraph), and
	// can be ignored by most users.
	CommitAt(commitTs uint64, callback func(error)) error
	Discard()
	Set([]byte, []byte) error
	Delete([]byte) error
	Get([]byte) (Item, error)
	NewKeyIterator(key []byte, iterOpt adapter.IteratorOptions) Iterator
	NewIterator(iterOpt adapter.IteratorOptions) Iterator
}