Chapter 35. The Information Schema

   Table of Contents

   35.1. The Schema
   35.2. Data Types
   35.3. information_schema_catalog_name
   35.4. administrable_role_​authorizations
   35.5. applicable_roles
   35.6. attributes
   35.7. character_sets
   35.8. check_constraint_routine_usage
   35.9. check_constraints
   35.10. collations
   35.11. collation_character_set_​applicability
   35.12. column_column_usage
   35.13. column_domain_usage
   35.14. column_options
   35.15. column_privileges
   35.16. column_udt_usage
   35.17. columns
   35.18. constraint_column_usage
   35.19. constraint_table_usage
   35.20. data_type_privileges
   35.21. domain_constraints
   35.22. domain_udt_usage
   35.23. domains
   35.24. element_types
   35.25. enabled_roles
   35.26. foreign_data_wrapper_options
   35.27. foreign_data_wrappers
   35.28. foreign_server_options
   35.29. foreign_servers
   35.30. foreign_table_options
   35.31. foreign_tables
   35.32. key_column_usage
   35.33. parameters
   35.34. referential_constraints
   35.35. role_column_grants
   35.36. role_routine_grants
   35.37. role_table_grants
   35.38. role_udt_grants
   35.39. role_usage_grants
   35.40. routine_column_usage
   35.41. routine_privileges
   35.42. routine_routine_usage
   35.43. routine_sequence_usage
   35.44. routine_table_usage
   35.45. routines
   35.46. schemata
   35.47. sequences
   35.48. sql_features
   35.49. sql_implementation_info
   35.50. sql_parts
   35.51. sql_sizing
   35.52. table_constraints
   35.53. table_privileges
   35.54. tables
   35.55. transforms
   35.56. triggered_update_columns
   35.57. triggers
   35.58. udt_privileges
   35.59. usage_privileges
   35.60. user_defined_types
   35.61. user_mapping_options
   35.62. user_mappings
   35.63. view_column_usage
   35.64. view_routine_usage
   35.65. view_table_usage
   35.66. views

   The information schema consists of a set of views that contain
   information about the objects defined in the current database. The
   information schema is defined in the SQL standard and can therefore be
   expected to be portable and remain stable — unlike the system catalogs,
   which are specific to PostgreSQL and are modeled after implementation
   concerns. The information schema views do not, however, contain
   information about PostgreSQL-specific features; to inquire about those
   you need to query the system catalogs or other PostgreSQL-specific
   views.

Note

   When querying the database for constraint information, it is possible
   for a standard-compliant query that expects to return one row to return
   several. This is because the SQL standard requires constraint names to
   be unique within a schema, but PostgreSQL does not enforce this
   restriction. PostgreSQL automatically-generated constraint names avoid
   duplicates in the same schema, but users can specify such duplicate
   names.

   This problem can appear when querying information schema views such as
   check_constraint_routine_usage, check_constraints, domain_constraints,
   and referential_constraints. Some other views have similar issues but
   contain the table name to help distinguish duplicate rows, e.g.,
   constraint_column_usage, constraint_table_usage, table_constraints.