| PostgreSQL 8.2.6 Documentation | ||||
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The columns of the information schema views use special data types that are defined in the information schema. These are defined as simple domains over ordinary built-in types. You should not use these types for work outside the information schema, but your applications must be prepared for them if they select from the information schema.
These types are:
A nonnegative integer.
A character string (without specific maximum length).
A character string. This type is used for SQL identifiers, the type character_data is used for any other kind of text data.
A domain over the type timestamp with time zone
Every column in the information schema has one of these four types.
Boolean (true/false) data is represented in the information schema by a column of type character_data that contains either YES or NO . (The information schema was invented before the type boolean was added to the SQL standard, so this convention is necessary to keep the information schema backward compatible.)