Copyright	(c) 2013 Leon P Smith
License	BSD3
Maintainer	Leon P Smith <leon@melding-monads.com>
Stability	experimental
Safe Haskell	None
Language	Haskell2010

Database.PostgreSQL.Simple.TypeInfo

Description

This module provides convenient and efficient access to parts of the pg_type metatable. At the moment, this requires PostgreSQL 8.4 if you need to work with types that do not appear in Static .

The current scheme could be more efficient, especially for some use cases. In particular, connection pools that use many user-added types and connect to a set of servers with identical (or at least compatible) pg_type and associated tables could share a common typeinfo cache, thus saving memory and communication between the client and server.

Synopsis

getTypeInfo :: Connection -> Oid -> IO TypeInfo
data TypeInfo
- = Basic {
  - typoid :: ! Oid
  - typcategory :: ! Char
  - typdelim :: ! Char
  - typname :: ! ByteString
  }
- | Array {
  - typoid :: ! Oid
  - typcategory :: ! Char
  - typdelim :: ! Char
  - typname :: ! ByteString
  - typelem :: ! TypeInfo
  }
- | Range {
  - typoid :: ! Oid
  - typcategory :: ! Char
  - typdelim :: ! Char
  - typname :: ! ByteString
  - rngsubtype :: ! TypeInfo
  }
- | Composite {
  - typoid :: ! Oid
  - typcategory :: ! Char
  - typdelim :: ! Char
  - typname :: ! ByteString
  - typrelid :: ! Oid
  - attributes :: !( Vector Attribute )
  }
data Attribute = Attribute {
- attname :: ! ByteString
- atttype :: ! TypeInfo
}

Documentation

getTypeInfo :: Connection -> Oid -> IO TypeInfo Source #

Returns the metadata of the type with a particular oid. To find this data, getTypeInfo first consults postgresql-simple's built-in staticTypeInfo table, then checks the connection's typeinfo cache. Finally, the database's pg_type table will be queried only if necessary, and the result will be stored in the connections's cache.

data TypeInfo Source #

A structure representing some of the metadata regarding a PostgreSQL type, mostly taken from the pg_type table.

Constructors

Basic
Fields typoid :: ! Oid typcategory :: ! Char typdelim :: ! Char typname :: ! ByteString
Array
Fields typoid :: ! Oid typcategory :: ! Char typdelim :: ! Char typname :: ! ByteString typelem :: ! TypeInfo
Range
Fields typoid :: ! Oid typcategory :: ! Char typdelim :: ! Char typname :: ! ByteString rngsubtype :: ! TypeInfo
Composite
Fields typoid :: ! Oid typcategory :: ! Char typdelim :: ! Char typname :: ! ByteString typrelid :: ! Oid attributes :: !( Vector Attribute )

Instances

Instances details

Show TypeInfo Source #
Instance details Defined in Database.PostgreSQL.Simple.TypeInfo.Types Methods showsPrec :: Int -> TypeInfo -> ShowS Source # show :: TypeInfo -> String Source # showList :: [ TypeInfo ] -> ShowS Source #

data Attribute Source #

Constructors

Attribute
Fields attname :: ! ByteString atttype :: ! TypeInfo

Instances

Instances details

Show Attribute Source #
Instance details Defined in Database.PostgreSQL.Simple.TypeInfo.Types Methods showsPrec :: Int -> Attribute -> ShowS Source # show :: Attribute -> String Source # showList :: [ Attribute ] -> ShowS Source #