Database.RocksDB

RocksDB Haskell binding.

The API closely follows the C-API of RocksDB.

Exported Types

data DB

Constructors

DB

Fields

• rocksDB :: !RocksDB
• columnFamilies :: ![ColumnFamily]
• readOpts :: !ReadOpts
• writeOpts :: !WriteOpts

data BatchOp

Constructors

Put !ByteString !ByteString

Del !ByteString

PutCF !ColumnFamily !ByteString !ByteString

DelCF !ColumnFamily !ByteString

Instances

Eq BatchOp

Defined in Database.RocksDB.Base

Methods

(==) :: BatchOp -> BatchOp -> Bool

(/=) :: BatchOp -> BatchOp -> Bool

Show BatchOp

Defined in Database.RocksDB.Base

Methods

showsPrec :: Int -> BatchOp -> ShowS

show :: BatchOp -> String

showList :: [BatchOp] -> ShowS

type Range = (ByteString, ByteString)

type ColumnFamily = Ptr LColumnFamily

Options

data Config

Constructors

Config

Fields

• createIfMissing :: !Bool
• errorIfExists :: !Bool
• paranoidChecks :: !Bool
• maxFiles :: !(Maybe Int)
• prefixLength :: !(Maybe Int)
• bloomFilter :: !Bool

Instances

Eq Config

Defined in Database.RocksDB.Internal

Methods

(==) :: Config -> Config -> Bool

(/=) :: Config -> Config -> Bool

Show Config

Defined in Database.RocksDB.Internal

Methods

showsPrec :: Int -> Config -> ShowS

show :: Config -> String

showList :: [Config] -> ShowS

Default Config

Defined in Database.RocksDB.Internal

Methods

def :: Config

Basic Database Manipulations

withDB :: MonadUnliftIO m => FilePath -> Config -> (DB -> m a) -> m a

Open a database.

The returned handle should be released with close.

withDBCF :: MonadUnliftIO m => FilePath -> Config -> [(String, Config)] -> (DB -> m a) -> m a

put :: MonadIO m => DB -> ByteString -> ByteString -> m ()

Write a key/value pair.

putCF :: MonadIO m => DB -> ColumnFamily -> ByteString -> ByteString -> m ()

delete :: MonadIO m => DB -> ByteString -> m ()

deleteCF :: MonadIO m => DB -> ColumnFamily -> ByteString -> m ()

write :: MonadIO m => DB -> [BatchOp] -> m ()

Perform a batch mutation.

get :: MonadIO m => DB -> ByteString -> m (Maybe ByteString)

Read a value by key.

getCF :: MonadIO m => DB -> ColumnFamily -> ByteString -> m (Maybe ByteString)

withSnapshot :: MonadUnliftIO m => DB -> (DB -> m a) -> m a

Run an action with a snapshot of the database. The DB object is not valid after the action ends.

Administrative Functions

data Property

Properties exposed by RocksDB

Constructors

NumFilesAtLevel Int

Stats

SSTables

Instances

Eq Property

Defined in Database.RocksDB.Base

Methods

(==) :: Property -> Property -> Bool

(/=) :: Property -> Property -> Bool

Show Property

Defined in Database.RocksDB.Base

Methods

showsPrec :: Int -> Property -> ShowS

show :: Property -> String

showList :: [Property] -> ShowS

getProperty :: MonadIO m => DB -> Property -> m (Maybe ByteString)

Get a DB property.

destroy :: MonadIO m => FilePath -> Options -> m ()

Destroy the given RocksDB database.

repair :: MonadIO m => FilePath -> Options -> m ()

Repair the given RocksDB database.

approximateSize :: MonadIO m => DB -> Range -> m Int64

Inspect the approximate sizes of the different levels.

Iteration

type Iterator = Ptr LIterator

withIter :: MonadUnliftIO m => DB -> (Iterator -> m a) -> m a

Create Iterator and use it.

Note that an Iterator creates a snapshot of the database implicitly, so updates written after the iterator was created are not visible. You may, however, specify an older Snapshot in the ReadOptions.

Iterator should not be used after computation ends.

withIterCF :: MonadUnliftIO m => DB -> ColumnFamily -> (Iterator -> m a) -> m a

iterEntry :: MonadIO m => Iterator -> m (Maybe (ByteString, ByteString))

Return the current entry as a pair, if the iterator is currently positioned at an entry, ie. iterValid.

iterFirst :: MonadIO m => Iterator -> m ()

Position at the first key in the source. The iterator is valid after this call iff the source is not empty.

iterGetError :: MonadIO m => Iterator -> m (Maybe ByteString)

Check for errors

Note that this captures somewhat severe errors such as a corrupted database.

iterKey :: MonadIO m => Iterator -> m (Maybe ByteString)

Return the key for the current entry if the iterator is currently positioned at an entry, ie. iterValid.

iterLast :: MonadIO m => Iterator -> m ()

Position at the last key in the source. The iterator is valid after this call iff the source is not empty.

iterNext :: MonadIO m => Iterator -> m ()

Moves to the next entry in the source. After this call, iterValid is true iff the iterator was not positioned at the last entry in the source.

If the iterator is not valid, this function does nothing. Note that this is a shortcoming of the C API: an iterPrev might still be possible, but we can't determine if we're at the last or first entry.

iterPrev :: MonadIO m => Iterator -> m ()

Moves to the previous entry in the source. After this call, iterValid is true iff the iterator was not positioned at the first entry in the source.

If the iterator is not valid, this function does nothing. Note that this is a shortcoming of the C API: an iterNext might still be possible, but we can't determine if we're at the last or first entry.

iterSeek :: MonadIO m => Iterator -> ByteString -> m ()

Position at the first key in the source that is at or past target. The iterator is valid after this call iff the source contains an entry that comes at or past target.

iterValid :: MonadIO m => Iterator -> m Bool

An iterator is either positioned at a key/value pair, or not valid. This function returns true iff the iterator is valid.

iterValue :: MonadIO m => Iterator -> m (Maybe ByteString)

Return the value for the current entry if the iterator is currently positioned at an entry, ie. iterValid.