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

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

data Attribute Source #

Constructors

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

Instances

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