Database.PostgreSQL.Typed.Protocol

The Protocol module allows for direct, low-level communication with a PostgreSQL server over TCP/IP. You probably don't want to use this module directly.

Documentation

data PGDatabase

Information for how to connect to a database, to be passed to pgConnect.

Constructors

PGDatabase

Fields

pgDBHost :: HostName

The hostname (ignored if pgDBPort is UnixSocket)

pgDBPort :: PortID

The port, likely either PortNumber 5432 or UnixSocket "tmp.s.PGSQL.5432"

pgDBName :: String

The name of the database

pgDBUser :: String

pgDBPass :: String

pgDBDebug :: Bool

Log all low-level server messages

pgDBLogMessage :: MessageFields -> IO ()

How to log server notice messages (e.g., print . PGError)

Instances

Eq PGDatabase

defaultPGDatabase :: PGDatabase

A database connection with sane defaults: localhost:5432:postgres

data PGConnection

An established connection to the PostgreSQL server. These objects are not thread-safe and must only be used for a single request at a time.

data PGError

PGException is thrown upon encountering an ErrorResponse with severity of ERROR, FATAL, or PANIC. It holds the message of the error.

Constructors

PGError MessageFields

Instances

Show PGError

Exception PGError

Typeable * PGError

pgMessageCode :: MessageFields -> String

Message SQLState code. See http://www.postgresql.org/docs/current/static/errcodes-appendix.html.

pgTypeEnv :: PGConnection -> PGTypeEnv

pgConnect :: PGDatabase -> IO PGConnection

Connect to a PostgreSQL server.

pgDisconnect

Arguments

:: PGConnection

a handle from pgConnect

-> IO ()

Disconnect cleanly from the PostgreSQL server.

pgReconnect :: PGConnection -> PGDatabase -> IO PGConnection

Possibly re-open a connection to a different database, either reusing the connection if the given database is already connected or closing it and opening a new one. Regardless, the input connection must not be used afterwards.

pgDescribe

Arguments

:: PGConnection

-> String

SQL string

-> [OID]

Optional type specifications

-> Bool

Guess nullability, otherwise assume everything is

-> IO ([OID], [(String, OID, Bool)])

a list of parameter types, and a list of result field names, types, and nullability indicators.

Describe a SQL statement/query. A statement description consists of 0 or more parameter descriptions (a PostgreSQL type) and zero or more result field descriptions (for queries) (consist of the name of the field, the type of the field, and a nullability indicator).

pgSimpleQuery

Arguments

:: PGConnection

-> String

SQL string

-> IO (Int, Seq PGValues)

The number of rows affected and a list of result rows

A simple query is one which requires sending only a single SimpleQuery message to the PostgreSQL server. The query is sent as a single string; you cannot bind parameters. Note that queries can return 0 results (an empty list).

pgPreparedQuery

Arguments

:: PGConnection

-> String

SQL statement with placeholders

-> [OID]

Optional type specifications (only used for first call)

-> PGValues

Paremeters to bind to placeholders

-> [Bool]

Requested binary format for result columns

-> IO (Int, Seq PGValues)

Prepare a statement, bind it, and execute it. If the given statement has already been prepared (and not yet closed) on this connection, it will be re-used.

pgPreparedLazyQuery

Arguments

:: PGConnection

-> String

-> [OID]

-> PGValues

-> [Bool]

-> Word32

Chunk size (1 is common, 0 is all-at-once)

-> IO [PGValues]

Like pgPreparedQuery but requests results lazily in chunks of the given size. Does not use a named portal, so other requests may not intervene.

pgCloseStatement :: PGConnection -> String -> [OID] -> IO ()

Close a previously prepared query (if necessary).