Database.PostgreSQL.Simple.TypeInfo

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.

Documentation

getTypeInfo :: Connection -> Oid -> IO TypeInfo

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

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

Methods

showsPrec :: Int -> TypeInfo -> ShowS

show :: TypeInfo -> String

showList :: [TypeInfo] -> ShowS

data Attribute

Constructors

Attribute

Fields

• attname :: !ByteString
• atttype :: !TypeInfo

Instances

Show Attribute

Methods

showsPrec :: Int -> Attribute -> ShowS

show :: Attribute -> String

showList :: [Attribute] -> ShowS