Database.PostgreSQL.Simple.LargeObjects

Support for PostgreSQL's Large Objects; see http://www.postgresql.org/docs/9.1/static/largeobjects.html for more information.

Note that Large Object File Descriptors are only valid within a single database transaction, so if you are interested in using anything beyond loCreat, loCreate, and loUnlink, you will need to run the entire sequence of functions in a transaction. As loImport and loExport are simply C functions that call loCreat, loOpen, loRead, and loWrite, and do not perform any transaction handling themselves, they also need to be wrapped in an explicit transaction.

Documentation

loCreat :: Connection -> IO Oid

loCreate :: Connection -> Oid -> IO Oid

loImport :: Connection -> FilePath -> IO Oid

loImportWithOid :: Connection -> FilePath -> Oid -> IO Oid

loExport :: Connection -> Oid -> FilePath -> IO ()

loOpen :: Connection -> Oid -> IOMode -> IO LoFd

loWrite :: Connection -> LoFd -> ByteString -> IO Int

loRead :: Connection -> LoFd -> Int -> IO ByteString

loSeek :: Connection -> LoFd -> SeekMode -> Int -> IO Int

loTell :: Connection -> LoFd -> IO Int

loTruncate :: Connection -> LoFd -> Int -> IO ()

loClose :: Connection -> LoFd -> IO ()

loUnlink :: Connection -> Oid -> IO ()

newtype Oid

Constructors

Oid CUInt

Instances

Eq Oid

Ord Oid

Read Oid

Show Oid

Storable Oid

ToField Oid

FromField Oid

oid

data LoFd

LoFd is a Large Object (pseudo) File Descriptor. It is understood by libpq but not by operating system calls.

Instances

Eq LoFd

Ord LoFd

Show LoFd

data IOMode

See openFile

Constructors

ReadMode

WriteMode

AppendMode

ReadWriteMode

Instances

Enum IOMode

Eq IOMode

Ord IOMode

Read IOMode

Show IOMode

Ix IOMode

data SeekMode

A mode that determines the effect of hSeek hdl mode i.

Constructors

AbsoluteSeek

the position of hdl is set to i.

RelativeSeek

the position of hdl is set to offset i from the current position.

SeekFromEnd

the position of hdl is set to offset i from the end of the file.

Instances

Enum SeekMode

Eq SeekMode

Ord SeekMode

Read SeekMode

Show SeekMode

Ix SeekMode