org.rocksdb

Interface WriteBatchInterface

All Known Implementing Classes:

AbstractWriteBatch, WriteBatch, WriteBatchWithIndex

public interface WriteBatchInterface

Defines the interface for a Write Batch which holds a collection of updates to apply atomically to a DB.

Method Summary

Methods

Modifier and Type	Method and Description
void	clear() Clear all updates buffered in this batch
int	count() Returns the number of updates in the batch.
void	merge(byte[] key, byte[] value) Merge "value" with the existing value of "key" in the database.
void	merge(ColumnFamilyHandle columnFamilyHandle, byte[] key, byte[] value) Merge "value" with the existing value of "key" in given column family.
void	put(byte[] key, byte[] value) Store the mapping "key->value" in the database.
void	put(ColumnFamilyHandle columnFamilyHandle, byte[] key, byte[] value) Store the mapping "key->value" within given column family.
void	putLogData(byte[] blob) Append a blob of arbitrary size to the records in this batch.
void	remove(byte[] key) If the database contains a mapping for "key", erase it.
void	remove(ColumnFamilyHandle columnFamilyHandle, byte[] key) If column family contains a mapping for "key", erase it.
void	rollbackToSavePoint() Remove all entries in this batch (Put, Merge, Delete, PutLogData) since the most recent call to SetSavePoint() and removes the most recent save point.
void	setSavePoint() Records the state of the batch for future calls to RollbackToSavePoint().

Method Detail

count

int count()

Returns the number of updates in the batch.

Returns:

number of items in WriteBatch

put

void put(byte[] key,
       byte[] value)

Store the mapping "key->value" in the database.

Parameters:

key - the specified key to be inserted.

value - the value associated with the specified key.

put

void put(ColumnFamilyHandle columnFamilyHandle,
       byte[] key,
       byte[] value)

Store the mapping "key->value" within given column family.

Parameters:

columnFamilyHandle - ColumnFamilyHandle instance

key - the specified key to be inserted.

value - the value associated with the specified key.

merge

void merge(byte[] key,
         byte[] value)

Merge "value" with the existing value of "key" in the database. "key->merge(existing, value)"

Parameters:

key - the specified key to be merged.

value - the value to be merged with the current value for the specified key.

merge

void merge(ColumnFamilyHandle columnFamilyHandle,
         byte[] key,
         byte[] value)

Merge "value" with the existing value of "key" in given column family. "key->merge(existing, value)"

Parameters:

columnFamilyHandle - ColumnFamilyHandle instance

key - the specified key to be merged.

value - the value to be merged with the current value for the specified key.

remove

void remove(byte[] key)

If the database contains a mapping for "key", erase it. Else do nothing.

Parameters:

key - Key to delete within database

remove

void remove(ColumnFamilyHandle columnFamilyHandle,
          byte[] key)

If column family contains a mapping for "key", erase it. Else do nothing.

Parameters:

columnFamilyHandle - ColumnFamilyHandle instance

key - Key to delete within database

putLogData

void putLogData(byte[] blob)

Append a blob of arbitrary size to the records in this batch. The blob will be stored in the transaction log but not in any other file. In particular, it will not be persisted to the SST files. When iterating over this WriteBatch, WriteBatch::Handler::LogData will be called with the contents of the blob as it is encountered. Blobs, puts, deletes, and merges will be encountered in the same order in thich they were inserted. The blob will NOT consume sequence number(s) and will NOT increase the count of the batch Example application: add timestamps to the transaction log for use in replication.

Parameters:

blob - binary object to be inserted

clear

void clear()

Clear all updates buffered in this batch

setSavePoint

void setSavePoint()

Records the state of the batch for future calls to RollbackToSavePoint(). May be called multiple times to set multiple save points.

rollbackToSavePoint

void rollbackToSavePoint()
                         throws RocksDBException

Remove all entries in this batch (Put, Merge, Delete, PutLogData) since the most recent call to SetSavePoint() and removes the most recent save point.

Throws:

RocksDBException - if there is no previous call to SetSavePoint()