information schema 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 modelled 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. 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. The information schema itself is a schema named information_schema. This schema automatically exists in all databases. The owner of this schema is the initial database user in the cluster, and that user naturally has all the privileges on this schema, including the ability to drop it (but the space savings achieved by that are minuscule). By default, the information schema is not in the schema search path, so you need to access all objects in it through qualified names. Since the names of some of the objects in the information schema are generic names that might occur in user applications, you should be careful if you want to put the information schema in the path. 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: cardinal_number A nonnegative integer. character_data A character string (without specific maximum length). sql_identifier A character string. This type is used for SQL identifiers, the type character_data is used for any other kind of text data. time_stamp A domain over the type timestamp with time zone yes_or_no A character string domain that contains either YES or NO. This is used to represent Boolean (true/false) data in the information schema. (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.) Every column in the information schema has one of these five types. information_schema_catalog_name is a table that always contains one row and one column containing the name of the current database (current catalog, in SQL terminology). Name Data Type Description catalog_name sql_identifier Name of the database that contains this information schema The view administrable_role_authorizations identifies all roles that the current user has the admin option for. Name Data Type Description grantee sql_identifier Name of the role to which this role membership was granted (can be the current user, or a different role in case of nested role memberships) role_name sql_identifier Name of a role is_grantable yes_or_no Always YES The view applicable_roles identifies all roles whose privileges the current user can use. This means there is some chain of role grants from the current user to the role in question. The current user itself is also an applicable role. The set of applicable roles is generally used for permission checking. applicable role roleapplicable Name Data Type Description grantee sql_identifier Name of the role to which this role membership was granted (can be the current user, or a different role in case of nested role memberships) role_name sql_identifier Name of a role is_grantable yes_or_no YES if the grantee has the admin option on the role, NO if not The view attributes contains information about the attributes of composite data types defined in the database. (Note that the view does not give information about table columns, which are sometimes called attributes in PostgreSQL contexts.) Name Data Type Description udt_catalog sql_identifier Name of the database containing the data type (always the current database) udt_schema sql_identifier Name of the schema containing the data type udt_name sql_identifier Name of the data type attribute_name sql_identifier Name of the attribute ordinal_position cardinal_number Ordinal position of the attribute within the data type (count starts at 1) attribute_default character_data Default expression of the attribute is_nullable yes_or_no YES if the attribute is possibly nullable, NO if it is known not nullable. data_type character_data Data type of the attribute, if it is a built-in type, or ARRAY if it is some array (in that case, see the view element_types), else USER-DEFINED (in that case, the type is identified in attribute_udt_name and associated columns). character_maximum_length cardinal_number If data_type identifies a character or bit string type, the declared maximum length; null for all other data types or if no maximum length was declared. character_octet_length cardinal_number If data_type identifies a character type, the maximum possible length in octets (bytes) of a datum; null for all other data types. The maximum octet length depends on the declared character maximum length (see above) and the server encoding. numeric_precision cardinal_number If data_type identifies a numeric type, this column contains the (declared or implicit) precision of the type for this attribute. The precision indicates the number of significant digits. It can be expressed in decimal (base 10) or binary (base 2) terms, as specified in the column numeric_precision_radix. For all other data types, this column is null. numeric_precision_radix cardinal_number If data_type identifies a numeric type, this column indicates in which base the values in the columns numeric_precision and numeric_scale are expressed. The value is either 2 or 10. For all other data types, this column is null. numeric_scale cardinal_number If data_type identifies an exact numeric type, this column contains the (declared or implicit) scale of the type for this attribute. The scale indicates the number of significant digits to the right of the decimal point. It can be expressed in decimal (base 10) or binary (base 2) terms, as specified in the column numeric_precision_radix. For all other data types, this column is null. datetime_precision cardinal_number If data_type identifies a date, time, timestamp, or interval type, this column contains the (declared or implicit) fractional seconds precision of the type for this attribute, that is, the number of decimal digits maintained following the decimal point in the seconds value. For all other data types, this column is null. interval_type character_data Not yet implemented interval_precision character_data Not yet implemented attribute_udt_catalog sql_identifier Name of the database that the attribute data type is defined in (always the current database) attribute_udt_schema sql_identifier Name of the schema that the attribute data type is defined in attribute_udt_name sql_identifier Name of the attribute data type scope_catalog sql_identifier Applies to a feature not available in PostgreSQL scope_schema sql_identifier Applies to a feature not available in PostgreSQL scope_name sql_identifier Applies to a feature not available in PostgreSQL maximum_cardinality cardinal_number Always null, because arrays always have unlimited maximum cardinality in PostgreSQL dtd_identifier sql_identifier An identifier of the data type descriptor of the column, unique among the data type descriptors pertaining to the table. This is mainly useful for joining with other instances of such identifiers. (The specific format of the identifier is not defined and not guaranteed to remain the same in future versions.) is_derived_reference_attribute yes_or_no Applies to a feature not available in PostgreSQL See also under , a similarly structured view, for further information on some of the columns. The view character_sets identifies the character sets available in the current database. Since PostgreSQL does not support multiple character sets within one database, this view only shows one, which is the database encoding. Take note of how the following terms are used in the SQL standard: character repertoire An abstract collection of characters, for example UNICODE, UCS, or LATIN1. Not exposed as an SQL object, but visible in this view. character encoding form An encoding of some character repertoire. Most older character repertoires only use one encoding form, and so there are no separate names for them (e.g., LATIN1 is an encoding form applicable to the LATIN1 repertoire). But for example Unicode has the encoding forms UTF8, UTF16, etc. (not all supported by PostgreSQL). Encoding forms are not exposed as an SQL object, but are visible in this view. character set A named SQL object that identifies a character repertoire, a character encoding, and a default collation. A predefined character set would typically have the same name as an encoding form, but users could define other names. For example, the character set UTF8 would typically identify the character repertoire UCS, encoding form UTF8, and some default collation. You can think of an encoding in PostgreSQL either as a character set or a character encoding form. They will have the same name, and there can only be one in one database. Name Data Type Description character_set_catalog sql_identifier Character sets are currently not implemented as schema objects, so this column is null. character_set_schema sql_identifier Character sets are currently not implemented as schema objects, so this column is null. character_set_name sql_identifier Name of the character set, currently implemented as showing the name of the database encoding character_repertoire sql_identifier Character repertoire, showing UCS if the encoding is UTF8, else just the encoding name form_of_use sql_identifier Character encoding form, same as the database encoding default_collate_catalog sql_identifier Name of the database containing the default collation (always the current database, if any collation is identified) default_collate_schema sql_identifier Name of the schema containing the default collation default_collate_name sql_identifier Name of the default collation. The default collation is identified as the collation that matches the COLLATE and CTYPE settings of the current database. If there is no such collation, then this column and the associated schema and catalog columns are null. The view check_constraint_routine_usage identifies routines (functions and procedures) that are used by a check constraint. Only those routines are shown that are owned by a currently enabled role. Name Data Type Description constraint_catalog sql_identifier Name of the database containing the constraint (always the current database) constraint_schema sql_identifier Name of the schema containing the constraint constraint_name sql_identifier Name of the constraint specific_catalog sql_identifier Name of the database containing the function (always the current database) specific_schema sql_identifier Name of the schema containing the function specific_name sql_identifier The specific name of the function. See for more information. The view check_constraints contains all check constraints, either defined on a table or on a domain, that are owned by a currently enabled role. (The owner of the table or domain is the owner of the constraint.) Name Data Type Description constraint_catalog sql_identifier Name of the database containing the constraint (always the current database) constraint_schema sql_identifier Name of the schema containing the constraint constraint_name sql_identifier Name of the constraint check_clause character_data The check expression of the check constraint The view collations contains the collations available in the current database. Name Data Type Description collation_catalog sql_identifier Name of the database containing the collation (always the current database) collation_schema sql_identifier Name of the schema containing the collation collation_name sql_identifier Name of the default collation pad_attribute character_data Always NO PAD (The alternative PAD SPACE is not supported by PostgreSQL.) The view collation_character_set_applicability identifies which character set the available collations are applicable to. In PostgreSQL, there is only one character set per database (see explanation in ), so this view does not provide much useful information. Name Data Type Description collation_catalog sql_identifier Name of the database containing the collation (always the current database) collation_schema sql_identifier Name of the schema containing the collation collation_name sql_identifier Name of the default collation character_set_catalog sql_identifier Character sets are currently not implemented as schema objects, so this column is null character_set_schema sql_identifier Character sets are currently not implemented as schema objects, so this column is null character_set_name sql_identifier Name of the character set The view column_domain_usage identifies all columns (of a table or a view) that make use of some domain defined in the current database and owned by a currently enabled role. Name Data Type Description domain_catalog sql_identifier Name of the database containing the domain (always the current database) domain_schema sql_identifier Name of the schema containing the domain domain_name sql_identifier Name of the domain table_catalog sql_identifier Name of the database containing the table (always the current database) table_schema sql_identifier Name of the schema containing the table table_name sql_identifier Name of the table column_name sql_identifier Name of the column The view column_privileges identifies all privileges granted on columns to a currently enabled role or by a currently enabled role. There is one row for each combination of column, grantor, and grantee. If a privilege has been granted on an entire table, it will show up in this view as a grant for each column, but only for the privilege types where column granularity is possible: SELECT, INSERT, UPDATE, REFERENCES. Name Data Type Description grantor sql_identifier Name of the role that granted the privilege grantee sql_identifier Name of the role that the privilege was granted to table_catalog sql_identifier Name of the database that contains the table that contains the column (always the current database) table_schema sql_identifier Name of the schema that contains the table that contains the column table_name sql_identifier Name of the table that contains the column column_name sql_identifier Name of the column privilege_type character_data Type of the privilege: SELECT, INSERT, UPDATE, or REFERENCES is_grantable yes_or_no YES if the privilege is grantable, NO if not The view column_udt_usage identifies all columns that use data types owned by a currently enabled role. Note that in PostgreSQL, built-in data types behave like user-defined types, so they are included here as well. See also for details. Name Data Type Description udt_catalog sql_identifier Name of the database that the column data type (the underlying type of the domain, if applicable) is defined in (always the current database) udt_schema sql_identifier Name of the schema that the column data type (the underlying type of the domain, if applicable) is defined in udt_name sql_identifier Name of the column data type (the underlying type of the domain, if applicable) table_catalog sql_identifier Name of the database containing the table (always the current database) table_schema sql_identifier Name of the schema containing the table table_name sql_identifier Name of the table column_name sql_identifier Name of the column The view columns contains information about all table columns (or view columns) in the database. System columns (oid, etc.) are not included. Only those columns are shown that the current user has access to (by way of being the owner or having some privilege). Name Data Type Description table_catalog sql_identifier Name of the database containing the table (always the current database) table_schema sql_identifier Name of the schema containing the table table_name sql_identifier Name of the table column_name sql_identifier Name of the column ordinal_position cardinal_number Ordinal position of the column within the table (count starts at 1) column_default character_data Default expression of the column is_nullable yes_or_no YES if the column is possibly nullable, NO if it is known not nullable. A not-null constraint is one way a column can be known not nullable, but there can be others. data_type character_data Data type of the column, if it is a built-in type, or ARRAY if it is some array (in that case, see the view element_types), else USER-DEFINED (in that case, the type is identified in udt_name and associated columns). If the column is based on a domain, this column refers to the type underlying the domain (and the domain is identified in domain_name and associated columns). character_maximum_length cardinal_number If data_type identifies a character or bit string type, the declared maximum length; null for all other data types or if no maximum length was declared. character_octet_length cardinal_number If data_type identifies a character type, the maximum possible length in octets (bytes) of a datum; null for all other data types. The maximum octet length depends on the declared character maximum length (see above) and the server encoding. numeric_precision cardinal_number If data_type identifies a numeric type, this column contains the (declared or implicit) precision of the type for this column. The precision indicates the number of significant digits. It can be expressed in decimal (base 10) or binary (base 2) terms, as specified in the column numeric_precision_radix. For all other data types, this column is null. numeric_precision_radix cardinal_number If data_type identifies a numeric type, this column indicates in which base the values in the columns numeric_precision and numeric_scale are expressed. The value is either 2 or 10. For all other data types, this column is null. numeric_scale cardinal_number If data_type identifies an exact numeric type, this column contains the (declared or implicit) scale of the type for this column. The scale indicates the number of significant digits to the right of the decimal point. It can be expressed in decimal (base 10) or binary (base 2) terms, as specified in the column numeric_precision_radix. For all other data types, this column is null. datetime_precision cardinal_number If data_type identifies a date, time, timestamp, or interval type, this column contains the (declared or implicit) fractional seconds precision of the type for this column, that is, the number of decimal digits maintained following the decimal point in the seconds value. For all other data types, this column is null. interval_type character_data Not yet implemented interval_precision character_data Not yet implemented character_set_catalog sql_identifier Applies to a feature not available in PostgreSQL character_set_schema sql_identifier Applies to a feature not available in PostgreSQL character_set_name sql_identifier Applies to a feature not available in PostgreSQL collation_catalog sql_identifier Applies to a feature not available in PostgreSQL collation_schema sql_identifier Applies to a feature not available in PostgreSQL collation_name sql_identifier Applies to a feature not available in PostgreSQL domain_catalog sql_identifier If the column has a domain type, the name of the database that the domain is defined in (always the current database), else null. domain_schema sql_identifier If the column has a domain type, the name of the schema that the domain is defined in, else null. domain_name sql_identifier If the column has a domain type, the name of the domain, else null. udt_catalog sql_identifier Name of the database that the column data type (the underlying type of the domain, if applicable) is defined in (always the current database) udt_schema sql_identifier Name of the schema that the column data type (the underlying type of the domain, if applicable) is defined in udt_name sql_identifier Name of the column data type (the underlying type of the domain, if applicable) scope_catalog sql_identifier Applies to a feature not available in PostgreSQL scope_schema sql_identifier Applies to a feature not available in PostgreSQL scope_name sql_identifier Applies to a feature not available in PostgreSQL maximum_cardinality cardinal_number Always null, because arrays always have unlimited maximum cardinality in PostgreSQL dtd_identifier sql_identifier An identifier of the data type descriptor of the column, unique among the data type descriptors pertaining to the table. This is mainly useful for joining with other instances of such identifiers. (The specific format of the identifier is not defined and not guaranteed to remain the same in future versions.) is_self_referencing yes_or_no Applies to a feature not available in PostgreSQL is_identity yes_or_no Applies to a feature not available in PostgreSQL identity_generation character_data Applies to a feature not available in PostgreSQL identity_start character_data Applies to a feature not available in PostgreSQL identity_increment character_data Applies to a feature not available in PostgreSQL identity_maximum character_data Applies to a feature not available in PostgreSQL identity_minimum character_data Applies to a feature not available in PostgreSQL identity_cycle yes_or_no Applies to a feature not available in PostgreSQL is_generated character_data Applies to a feature not available in PostgreSQL generation_expression character_data Applies to a feature not available in PostgreSQL is_updatable yes_or_no YES if the column is updatable, NO if not (Columns in base tables are always updatable, columns in views not necessarily) Since data types can be defined in a variety of ways in SQL, and PostgreSQL contains additional ways to define data types, their representation in the information schema can be somewhat difficult. The column data_type is supposed to identify the underlying built-in type of the column. In PostgreSQL, this means that the type is defined in the system catalog schema pg_catalog. This column might be useful if the application can handle the well-known built-in types specially (for example, format the numeric types differently or use the data in the precision columns). The columns udt_name, udt_schema, and udt_catalog always identify the underlying data type of the column, even if the column is based on a domain. (Since PostgreSQL treats built-in types like user-defined types, built-in types appear here as well. This is an extension of the SQL standard.) These columns should be used if an application wants to process data differently according to the type, because in that case it wouldn't matter if the column is really based on a domain. If the column is based on a domain, the identity of the domain is stored in the columns domain_name, domain_schema, and domain_catalog. If you want to pair up columns with their associated data types and treat domains as separate types, you could write coalesce(domain_name, udt_name), etc. The view constraint_column_usage identifies all columns in the current database that are used by some constraint. Only those columns are shown that are contained in a table owned by a currently enabled role. For a check constraint, this view identifies the columns that are used in the check expression. For a foreign key constraint, this view identifies the columns that the foreign key references. For a unique or primary key constraint, this view identifies the constrained columns. Name Data Type Description table_catalog sql_identifier Name of the database that contains the table that contains the column that is used by some constraint (always the current database) table_schema sql_identifier Name of the schema that contains the table that contains the column that is used by some constraint table_name sql_identifier Name of the table that contains the column that is used by some constraint column_name sql_identifier Name of the column that is used by some constraint constraint_catalog sql_identifier Name of the database that contains the constraint (always the current database) constraint_schema sql_identifier Name of the schema that contains the constraint constraint_name sql_identifier Name of the constraint The view constraint_table_usage identifies all tables in the current database that are used by some constraint and are owned by a currently enabled role. (This is different from the view table_constraints, which identifies all table constraints along with the table they are defined on.) For a foreign key constraint, this view identifies the table that the foreign key references. For a unique or primary key constraint, this view simply identifies the table the constraint belongs to. Check constraints and not-null constraints are not included in this view. Name Data Type Description table_catalog sql_identifier Name of the database that contains the table that is used by some constraint (always the current database) table_schema sql_identifier Name of the schema that contains the table that is used by some constraint table_name sql_identifier Name of the table that is used by some constraint constraint_catalog sql_identifier Name of the database that contains the constraint (always the current database) constraint_schema sql_identifier Name of the schema that contains the constraint constraint_name sql_identifier Name of the constraint The view data_type_privileges identifies all data type descriptors that the current user has access to, by way of being the owner of the described object or having some privilege for it. A data type descriptor is generated whenever a data type is used in the definition of a table column, a domain, or a function (as parameter or return type) and stores some information about how the data type is used in that instance (for example, the declared maximum length, if applicable). Each data type descriptor is assigned an arbitrary identifier that is unique among the data type descriptor identifiers assigned for one object (table, domain, function). This view is probably not useful for applications, but it is used to define some other views in the information schema. Name Data Type Description object_catalog sql_identifier Name of the database that contains the described object (always the current database) object_schema sql_identifier Name of the schema that contains the described object object_name sql_identifier Name of the described object object_type character_data The type of the described object: one of TABLE (the data type descriptor pertains to a column of that table), DOMAIN (the data type descriptors pertains to that domain), ROUTINE (the data type descriptor pertains to a parameter or the return data type of that function). dtd_identifier sql_identifier The identifier of the data type descriptor, which is unique among the data type descriptors for that same object. The view domain_constraints contains all constraints belonging to domains defined in the current database. Name Data Type Description constraint_catalog sql_identifier Name of the database that contains the constraint (always the current database) constraint_schema sql_identifier Name of the schema that contains the constraint constraint_name sql_identifier Name of the constraint domain_catalog sql_identifier Name of the database that contains the domain (always the current database) domain_schema sql_identifier Name of the schema that contains the domain domain_name sql_identifier Name of the domain is_deferrable yes_or_no YES if the constraint is deferrable, NO if not initially_deferred yes_or_no YES if the constraint is deferrable and initially deferred, NO if not The view domain_udt_usage identifies all domains that are based on data types owned by a currently enabled role. Note that in PostgreSQL, built-in data types behave like user-defined types, so they are included here as well. Name Data Type Description udt_catalog sql_identifier Name of the database that the domain data type is defined in (always the current database) udt_schema sql_identifier Name of the schema that the domain data type is defined in udt_name sql_identifier Name of the domain data type domain_catalog sql_identifier Name of the database that contains the domain (always the current database) domain_schema sql_identifier Name of the schema that contains the domain domain_name sql_identifier Name of the domain The view domains contains all domains defined in the current database. Name Data Type Description domain_catalog sql_identifier Name of the database that contains the domain (always the current database) domain_schema sql_identifier Name of the schema that contains the domain domain_name sql_identifier Name of the domain data_type character_data Data type of the domain, if it is a built-in type, or ARRAY if it is some array (in that case, see the view element_types), else USER-DEFINED (in that case, the type is identified in udt_name and associated columns). character_maximum_length cardinal_number If the domain has a character or bit string type, the declared maximum length; null for all other data types or if no maximum length was declared. character_octet_length cardinal_number If the domain has a character type, the maximum possible length in octets (bytes) of a datum; null for all other data types. The maximum octet length depends on the declared character maximum length (see above) and the server encoding. character_set_catalog sql_identifier Applies to a feature not available in PostgreSQL character_set_schema sql_identifier Applies to a feature not available in PostgreSQL character_set_name sql_identifier Applies to a feature not available in PostgreSQL collation_catalog sql_identifier Applies to a feature not available in PostgreSQL collation_schema sql_identifier Applies to a feature not available in PostgreSQL collation_name sql_identifier Applies to a feature not available in PostgreSQL numeric_precision cardinal_number If the domain has a numeric type, this column contains the (declared or implicit) precision of the type for this domain. The precision indicates the number of significant digits. It can be expressed in decimal (base 10) or binary (base 2) terms, as specified in the column numeric_precision_radix. For all other data types, this column is null. numeric_precision_radix cardinal_number If the domain has a numeric type, this column indicates in which base the values in the columns numeric_precision and numeric_scale are expressed. The value is either 2 or 10. For all other data types, this column is null. numeric_scale cardinal_number If the domain has an exact numeric type, this column contains the (declared or implicit) scale of the type for this domain. The scale indicates the number of significant digits to the right of the decimal point. It can be expressed in decimal (base 10) or binary (base 2) terms, as specified in the column numeric_precision_radix. For all other data types, this column is null. datetime_precision cardinal_number If data_type identifies a date, time, timestamp, or interval type, this column contains the (declared or implicit) fractional seconds precision of the type for this domain, that is, the number of decimal digits maintained following the decimal point in the seconds value. For all other data types, this column is null. interval_type character_data Not yet implemented interval_precision character_data Not yet implemented domain_default character_data Default expression of the domain udt_catalog sql_identifier Name of the database that the domain data type is defined in (always the current database) udt_schema sql_identifier Name of the schema that the domain data type is defined in udt_name sql_identifier Name of the domain data type scope_catalog sql_identifier Applies to a feature not available in PostgreSQL scope_schema sql_identifier Applies to a feature not available in PostgreSQL scope_name sql_identifier Applies to a feature not available in PostgreSQL maximum_cardinality cardinal_number Always null, because arrays always have unlimited maximum cardinality in PostgreSQL dtd_identifier sql_identifier An identifier of the data type descriptor of the domain, unique among the data type descriptors pertaining to the domain (which is trivial, because a domain only contains one data type descriptor). This is mainly useful for joining with other instances of such identifiers. (The specific format of the identifier is not defined and not guaranteed to remain the same in future versions.) The view element_types contains the data type descriptors of the elements of arrays. When a table column, composite-type attribute, domain, function parameter, or function return value is defined to be of an array type, the respective information schema view only contains ARRAY in the column data_type. To obtain information on the element type of the array, you can join the respective view with this view. For example, to show the columns of a table with data types and array element types, if applicable, you could do: SELECT c.column_name, c.data_type, e.data_type AS element_type FROM information_schema.columns c LEFT JOIN information_schema.element_types e ON ((c.table_catalog, c.table_schema, c.table_name, 'TABLE', c.dtd_identifier) = (e.object_catalog, e.object_schema, e.object_name, e.object_type, e.collection_type_identifier)) WHERE c.table_schema = '...' AND c.table_name = '...' ORDER BY c.ordinal_position; This view only includes objects that the current user has access to, by way of being the owner or having some privilege. Name Data Type Description object_catalog sql_identifier Name of the database that contains the object that uses the array being described (always the current database) object_schema sql_identifier Name of the schema that contains the object that uses the array being described object_name sql_identifier Name of the object that uses the array being described object_type character_data The type of the object that uses the array being described: one of TABLE (the array is used by a column of that table), USER-DEFINED TYPE (the array is used by an attribute of that composite type), DOMAIN (the array is used by that domain), ROUTINE (the array is used by a parameter or the return data type of that function). collection_type_identifier sql_identifier The identifier of the data type descriptor of the array being described. Use this to join with the dtd_identifier columns of other information schema views. data_type character_data Data type of the array elements, if it is a built-in type, else USER-DEFINED (in that case, the type is identified in udt_name and associated columns). character_maximum_length cardinal_number Always null, since this information is not applied to array element data types in PostgreSQL character_octet_length cardinal_number Always null, since this information is not applied to array element data types in PostgreSQL character_set_catalog sql_identifier Applies to a feature not available in PostgreSQL character_set_schema sql_identifier Applies to a feature not available in PostgreSQL character_set_name sql_identifier Applies to a feature not available in PostgreSQL collation_catalog sql_identifier Applies to a feature not available in PostgreSQL collation_schema sql_identifier Applies to a feature not available in PostgreSQL collation_name sql_identifier Applies to a feature not available in PostgreSQL numeric_precision cardinal_number Always null, since this information is not applied to array element data types in PostgreSQL numeric_precision_radix cardinal_number Always null, since this information is not applied to array element data types in PostgreSQL numeric_scale cardinal_number Always null, since this information is not applied to array element data types in PostgreSQL datetime_precision cardinal_number Always null, since this information is not applied to array element data types in PostgreSQL interval_type character_data Always null, since this information is not applied to array element data types in PostgreSQL interval_precision character_data Always null, since this information is not applied to array element data types in PostgreSQL domain_default character_data Not yet implemented udt_catalog sql_identifier Name of the database that the data type of the elements is defined in (always the current database) udt_schema sql_identifier Name of the schema that the data type of the elements is defined in udt_name sql_identifier Name of the data type of the elements scope_catalog sql_identifier Applies to a feature not available in PostgreSQL scope_schema sql_identifier Applies to a feature not available in PostgreSQL scope_name sql_identifier Applies to a feature not available in PostgreSQL maximum_cardinality cardinal_number Always null, because arrays always have unlimited maximum cardinality in PostgreSQL dtd_identifier sql_identifier An identifier of the data type descriptor of the element. This is currently not useful. The view enabled_roles identifies the currently enabled roles. The enabled roles are recursively defined as the current user together with all roles that have been granted to the enabled roles with automatic inheritance. In other words, these are all roles that the current user has direct or indirect, automatically inheriting membership in. enabled role roleenabled For permission checking, the set of applicable roles is applied, which can be broader than the set of enabled roles. So generally, it is better to use the view applicable_roles instead of this one; see also there. Name Data Type Description role_name sql_identifier Name of a role The view foreign_data_wrapper_options contains all the options defined for foreign-data wrappers in the current database. Only those foreign-data wrappers are shown that the current user has access to (by way of being the owner or having some privilege). Name Data Type Description foreign_data_wrapper_catalog sql_identifier Name of the database that the foreign-data wrapper is defined in (always the current database) foreign_data_wrapper_name sql_identifier Name of the foreign-data wrapper option_name sql_identifier Name of an option option_value character_data Value of the option The view foreign_data_wrappers contains all foreign-data wrappers defined in the current database. Only those foreign-data wrappers are shown that the current user has access to (by way of being the owner or having some privilege). Name Data Type Description foreign_data_wrapper_catalog sql_identifier Name of the database that contains the foreign-data wrapper (always the current database) foreign_data_wrapper_name sql_identifier Name of the foreign-data wrapper authorization_identifier sql_identifier Name of the owner of the foreign server library_name character_data File name of the library that implementing this foreign-data wrapper foreign_data_wrapper_language character_data Language used to implement this foreign-data wrapper The view foreign_server_options contains all the options defined for foreign servers in the current database. Only those foreign servers are shown that the current user has access to (by way of being the owner or having some privilege). Name Data Type Description foreign_server_catalog sql_identifier Name of the database that the foreign server is defined in (always the current database) foreign_server_name sql_identifier Name of the foreign server option_name sql_identifier Name of an option option_value character_data Value of the option The view foreign_servers contains all foreign servers defined in the current database. Only those foreign servers are shown that the current user has access to (by way of being the owner or having some privilege). Name Data Type Description foreign_server_catalog sql_identifier Name of the database that the foreign server is defined in (always the current database) foreign_server_name sql_identifier Name of the foreign server foreign_data_wrapper_catalog sql_identifier Name of the database that contains the foreign-data wrapper used by the foreign server (always the current database) foreign_data_wrapper_name sql_identifier Name of the foreign-data wrapper used by the foreign server foreign_server_type character_data Foreign server type information, if specified upon creation foreign_server_version character_data Foreign server version information, if specified upon creation authorization_identifier sql_identifier Name of the owner of the foreign server The view foreign_table_options contains all the options defined for foreign tables in the current database. Only those foreign tables are shown that the current user has access to (by way of being the owner or having some privilege). Name Data Type Description foreign_table_catalog sql_identifier Name of the database that contains the foreign table (always the current database) foreign_table_schema sql_identifier Name of the schema that contains the foreign table foreign_table_name sql_identifier Name of the foreign table foreign_server_catalog sql_identifier Name of the database that the foreign server is defined in (always the current database) foreign_server_name sql_identifier Name of the foreign server option_name sql_identifier Name of an option option_value character_data Value of the option The view foreign_tables contains all foreign tables defined in the current database. Only those foreign tables are shown that the current user has access to (by way of being the owner or having some privilege). Name Data Type Description foreign_table_catalog sql_identifier Name of the database that the foreign table is defined in (always the current database) foreign_table_schema sql_identifier Name of the schema that contains the foreign table foreign_table_name sql_identifier Name of the foreign table foreign_server_catalog sql_identifier Name of the database that the foreign server is defined in (always the current database) foreign_server_name sql_identifier Name of the foreign server The view key_column_usage identifies all columns in the current database that are restricted by some unique, primary key, or foreign key constraint. Check constraints are not included in this view. Only those columns are shown that the current user has access to, by way of being the owner or having some privilege. Name Data Type Description constraint_catalog sql_identifier Name of the database that contains the constraint (always the current database) constraint_schema sql_identifier Name of the schema that contains the constraint constraint_name sql_identifier Name of the constraint table_catalog sql_identifier Name of the database that contains the table that contains the column that is restricted by this constraint (always the current database) table_schema sql_identifier Name of the schema that contains the table that contains the column that is restricted by this constraint table_name sql_identifier Name of the table that contains the column that is restricted by this constraint column_name sql_identifier Name of the column that is restricted by this constraint ordinal_position cardinal_number Ordinal position of the column within the constraint key (count starts at 1) position_in_unique_constraint cardinal_number For a foreign-key constraint, ordinal position of the referenced column within its unique constraint (count starts at 1); otherwise null The view parameters contains information about the parameters (arguments) of all functions in the current database. Only those functions are shown that the current user has access to (by way of being the owner or having some privilege). Name Data Type Description specific_catalog sql_identifier Name of the database containing the function (always the current database) specific_schema sql_identifier Name of the schema containing the function specific_name sql_identifier The specific name of the function. See for more information. ordinal_position cardinal_number Ordinal position of the parameter in the argument list of the function (count starts at 1) parameter_mode character_data IN for input parameter, OUT for output parameter, and INOUT for input/output parameter. is_result yes_or_no Applies to a feature not available in PostgreSQL as_locator yes_or_no Applies to a feature not available in PostgreSQL parameter_name sql_identifier Name of the parameter, or null if the parameter has no name data_type character_data Data type of the parameter, if it is a built-in type, or ARRAY if it is some array (in that case, see the view element_types), else USER-DEFINED (in that case, the type is identified in udt_name and associated columns). character_maximum_length cardinal_number Always null, since this information is not applied to parameter data types in PostgreSQL character_octet_length cardinal_number Always null, since this information is not applied to parameter data types in PostgreSQL character_set_catalog sql_identifier Applies to a feature not available in PostgreSQL character_set_schema sql_identifier Applies to a feature not available in PostgreSQL character_set_name sql_identifier Applies to a feature not available in PostgreSQL collation_catalog sql_identifier Applies to a feature not available in PostgreSQL collation_schema sql_identifier Applies to a feature not available in PostgreSQL collation_name sql_identifier Applies to a feature not available in PostgreSQL numeric_precision cardinal_number Always null, since this information is not applied to parameter data types in PostgreSQL numeric_precision_radix cardinal_number Always null, since this information is not applied to parameter data types in PostgreSQL numeric_scale cardinal_number Always null, since this information is not applied to parameter data types in PostgreSQL datetime_precision cardinal_number Always null, since this information is not applied to parameter data types in PostgreSQL interval_type character_data Always null, since this information is not applied to parameter data types in PostgreSQL interval_precision character_data Always null, since this information is not applied to parameter data types in PostgreSQL udt_catalog sql_identifier Name of the database that the data type of the parameter is defined in (always the current database) udt_schema sql_identifier Name of the schema that the data type of the parameter is defined in udt_name sql_identifier Name of the data type of the parameter scope_catalog sql_identifier Applies to a feature not available in PostgreSQL scope_schema sql_identifier Applies to a feature not available in PostgreSQL scope_name sql_identifier Applies to a feature not available in PostgreSQL maximum_cardinality cardinal_number Always null, because arrays always have unlimited maximum cardinality in PostgreSQL dtd_identifier sql_identifier An identifier of the data type descriptor of the parameter, unique among the data type descriptors pertaining to the function. This is mainly useful for joining with other instances of such identifiers. (The specific format of the identifier is not defined and not guaranteed to remain the same in future versions.) The view referential_constraints contains all referential (foreign key) constraints in the current database. Only those constraints are shown for which the current user has write access to the referencing table (by way of being the owner or having some privilege other than SELECT). Name Data Type Description constraint_catalog sql_identifier Name of the database containing the constraint (always the current database) constraint_schema sql_identifier Name of the schema containing the constraint constraint_name sql_identifier Name of the constraint unique_constraint_catalog sql_identifier Name of the database that contains the unique or primary key constraint that the foreign key constraint references (always the current database) unique_constraint_schema sql_identifier Name of the schema that contains the unique or primary key constraint that the foreign key constraint references unique_constraint_name sql_identifier Name of the unique or primary key constraint that the foreign key constraint references match_option character_data Match option of the foreign key constraint: FULL, PARTIAL, or NONE. update_rule character_data Update rule of the foreign key constraint: CASCADE, SET NULL, SET DEFAULT, RESTRICT, or NO ACTION. delete_rule character_data Delete rule of the foreign key constraint: CASCADE, SET NULL, SET DEFAULT, RESTRICT, or NO ACTION. The view role_column_grants identifies all privileges granted on columns where the grantor or grantee is a currently enabled role. Further information can be found under column_privileges. The only effective difference between this view and column_privileges is that this view omits columns that have been made accessible to the current user by way of a grant to PUBLIC. Name Data Type Description grantor sql_identifier Name of the role that granted the privilege grantee sql_identifier Name of the role that the privilege was granted to table_catalog sql_identifier Name of the database that contains the table that contains the column (always the current database) table_schema sql_identifier Name of the schema that contains the table that contains the column table_name sql_identifier Name of the table that contains the column column_name sql_identifier Name of the column privilege_type character_data Type of the privilege: SELECT, INSERT, UPDATE, or REFERENCES is_grantable yes_or_no YES if the privilege is grantable, NO if not The view role_routine_grants identifies all privileges granted on functions where the grantor or grantee is a currently enabled role. Further information can be found under routine_privileges. The only effective difference between this view and routine_privileges is that this view omits functions that have been made accessible to the current user by way of a grant to PUBLIC. Name Data Type Description grantor sql_identifier Name of the role that granted the privilege grantee sql_identifier Name of the role that the privilege was granted to specific_catalog sql_identifier Name of the database containing the function (always the current database) specific_schema sql_identifier Name of the schema containing the function specific_name sql_identifier The specific name of the function. See for more information. routine_catalog sql_identifier Name of the database containing the function (always the current database) routine_schema sql_identifier Name of the schema containing the function routine_name sql_identifier Name of the function (might be duplicated in case of overloading) privilege_type character_data Always EXECUTE (the only privilege type for functions) is_grantable yes_or_no YES if the privilege is grantable, NO if not The view role_table_grants identifies all privileges granted on tables or views where the grantor or grantee is a currently enabled role. Further information can be found under table_privileges. The only effective difference between this view and table_privileges is that this view omits tables that have been made accessible to the current user by way of a grant to PUBLIC. Name Data Type Description grantor sql_identifier Name of the role that granted the privilege grantee sql_identifier Name of the role that the privilege was granted to table_catalog sql_identifier Name of the database that contains the table (always the current database) table_schema sql_identifier Name of the schema that contains the table table_name sql_identifier Name of the table privilege_type character_data Type of the privilege: SELECT, INSERT, UPDATE, DELETE, TRUNCATE, REFERENCES, or TRIGGER is_grantable yes_or_no YES if the privilege is grantable, NO if not with_hierarchy yes_or_no Applies to a feature not available in PostgreSQL The view role_udt_grants is intended to identify USAGE privileges granted on user-defined types where the grantor or grantee is a currently enabled role. Further information can be found under udt_privileges. The only effective difference between this view and udt_privileges is that this view omits objects that have been made accessible to the current user by way of a grant to PUBLIC. Since data types do not have real privileges in PostgreSQL, but only an implicit grant to PUBLIC, this view is empty. Name Data Type Description grantor sql_identifier The name of the role that granted the privilege grantee sql_identifier The name of the role that the privilege was granted to udt_catalog sql_identifier Name of the database containing the type (always the current database) udt_schema sql_identifier Name of the schema containing the type udt_name sql_identifier Name of the type privilege_type character_data Always TYPE USAGE is_grantable yes_or_no YES if the privilege is grantable, NO if not The view role_usage_grants identifies USAGE privileges granted on various kinds of objects where the grantor or grantee is a currently enabled role. Further information can be found under usage_privileges. The only effective difference between this view and usage_privileges is that this view omits objects that have been made accessible to the current user by way of a grant to PUBLIC. Name Data Type Description grantor sql_identifier The name of the role that granted the privilege grantee sql_identifier The name of the role that the privilege was granted to object_catalog sql_identifier Name of the database containing the object (always the current database) object_schema sql_identifier Name of the schema containing the object, if applicable, else an empty string object_name sql_identifier Name of the object object_type character_data COLLATION or DOMAIN or FOREIGN DATA WRAPPER or FOREIGN SERVER privilege_type character_data Always USAGE is_grantable yes_or_no YES if the privilege is grantable, NO if not The view routine_privileges identifies all privileges granted on functions to a currently enabled role or by a currently enabled role. There is one row for each combination of function, grantor, and grantee. Name Data Type Description grantor sql_identifier Name of the role that granted the privilege grantee sql_identifier Name of the role that the privilege was granted to specific_catalog sql_identifier Name of the database containing the function (always the current database) specific_schema sql_identifier Name of the schema containing the function specific_name sql_identifier The specific name of the function. See for more information. routine_catalog sql_identifier Name of the database containing the function (always the current database) routine_schema sql_identifier Name of the schema containing the function routine_name sql_identifier Name of the function (might be duplicated in case of overloading) privilege_type character_data Always EXECUTE (the only privilege type for functions) is_grantable yes_or_no YES if the privilege is grantable, NO if not The view routines contains all functions in the current database. Only those functions are shown that the current user has access to (by way of being the owner or having some privilege). Name Data Type Description specific_catalog sql_identifier Name of the database containing the function (always the current database) specific_schema sql_identifier Name of the schema containing the function specific_name sql_identifier The specific name of the function. This is a name that uniquely identifies the function in the schema, even if the real name of the function is overloaded. The format of the specific name is not defined, it should only be used to compare it to other instances of specific routine names. routine_catalog sql_identifier Name of the database containing the function (always the current database) routine_schema sql_identifier Name of the schema containing the function routine_name sql_identifier Name of the function (might be duplicated in case of overloading) routine_type character_data Always FUNCTION (In the future there might be other types of routines.) module_catalog sql_identifier Applies to a feature not available in PostgreSQL module_schema sql_identifier Applies to a feature not available in PostgreSQL module_name sql_identifier Applies to a feature not available in PostgreSQL udt_catalog sql_identifier Applies to a feature not available in PostgreSQL udt_schema sql_identifier Applies to a feature not available in PostgreSQL udt_name sql_identifier Applies to a feature not available in PostgreSQL data_type character_data Return data type of the function, if it is a built-in type, or ARRAY if it is some array (in that case, see the view element_types), else USER-DEFINED (in that case, the type is identified in type_udt_name and associated columns). character_maximum_length cardinal_number Always null, since this information is not applied to return data types in PostgreSQL character_octet_length cardinal_number Always null, since this information is not applied to return data types in PostgreSQL character_set_catalog sql_identifier Applies to a feature not available in PostgreSQL character_set_schema sql_identifier Applies to a feature not available in PostgreSQL character_set_name sql_identifier Applies to a feature not available in PostgreSQL collation_catalog sql_identifier Applies to a feature not available in PostgreSQL collation_schema sql_identifier Applies to a feature not available in PostgreSQL collation_name sql_identifier Applies to a feature not available in PostgreSQL numeric_precision cardinal_number Always null, since this information is not applied to return data types in PostgreSQL numeric_precision_radix cardinal_number Always null, since this information is not applied to return data types in PostgreSQL numeric_scale cardinal_number Always null, since this information is not applied to return data types in PostgreSQL datetime_precision cardinal_number Always null, since this information is not applied to return data types in PostgreSQL interval_type character_data Always null, since this information is not applied to return data types in PostgreSQL interval_precision character_data Always null, since this information is not applied to return data types in PostgreSQL type_udt_catalog sql_identifier Name of the database that the return data type of the function is defined in (always the current database) type_udt_schema sql_identifier Name of the schema that the return data type of the function is defined in type_udt_name sql_identifier Name of the return data type of the function scope_catalog sql_identifier Applies to a feature not available in PostgreSQL scope_schema sql_identifier Applies to a feature not available in PostgreSQL scope_name sql_identifier Applies to a feature not available in PostgreSQL maximum_cardinality cardinal_number Always null, because arrays always have unlimited maximum cardinality in PostgreSQL dtd_identifier sql_identifier An identifier of the data type descriptor of the return data type of this function, unique among the data type descriptors pertaining to the function. This is mainly useful for joining with other instances of such identifiers. (The specific format of the identifier is not defined and not guaranteed to remain the same in future versions.) routine_body character_data If the function is an SQL function, then SQL, else EXTERNAL. routine_definition character_data The source text of the function (null if the function is not owned by a currently enabled role). (According to the SQL standard, this column is only applicable if routine_body is SQL, but in PostgreSQL it will contain whatever source text was specified when the function was created.) external_name character_data If this function is a C function, then the external name (link symbol) of the function; else null. (This works out to be the same value that is shown in routine_definition.) external_language character_data The language the function is written in parameter_style character_data Always GENERAL (The SQL standard defines other parameter styles, which are not available in PostgreSQL.) is_deterministic yes_or_no If the function is declared immutable (called deterministic in the SQL standard), then YES, else NO. (You cannot query the other volatility levels available in PostgreSQL through the information schema.) sql_data_access character_data Always MODIFIES, meaning that the function possibly modifies SQL data. This information is not useful for PostgreSQL. is_null_call yes_or_no If the function automatically returns null if any of its arguments are null, then YES, else NO. sql_path character_data Applies to a feature not available in PostgreSQL schema_level_routine yes_or_no Always YES (The opposite would be a method of a user-defined type, which is a feature not available in PostgreSQL.) max_dynamic_result_sets cardinal_number Applies to a feature not available in PostgreSQL is_user_defined_cast yes_or_no Applies to a feature not available in PostgreSQL is_implicitly_invocable yes_or_no Applies to a feature not available in PostgreSQL security_type character_data If the function runs with the privileges of the current user, then INVOKER, if the function runs with the privileges of the user who defined it, then DEFINER. to_sql_specific_catalog sql_identifier Applies to a feature not available in PostgreSQL to_sql_specific_schema sql_identifier Applies to a feature not available in PostgreSQL to_sql_specific_name sql_identifier Applies to a feature not available in PostgreSQL as_locator yes_or_no Applies to a feature not available in PostgreSQL created time_stamp Applies to a feature not available in PostgreSQL last_altered time_stamp Applies to a feature not available in PostgreSQL new_savepoint_level yes_or_no Applies to a feature not available in PostgreSQL is_udt_dependent yes_or_no Applies to a feature not available in PostgreSQL result_cast_from_data_type character_data Applies to a feature not available in PostgreSQL result_cast_as_locator yes_or_no Applies to a feature not available in PostgreSQL result_cast_char_max_length cardinal_number Applies to a feature not available in PostgreSQL result_cast_char_octet_length character_data Applies to a feature not available in PostgreSQL result_cast_char_set_catalog sql_identifier Applies to a feature not available in PostgreSQL result_cast_char_set_schema sql_identifier Applies to a feature not available in PostgreSQL result_cast_char_set_name sql_identifier Applies to a feature not available in PostgreSQL result_cast_collation_catalog sql_identifier Applies to a feature not available in PostgreSQL result_cast_collation_schema sql_identifier Applies to a feature not available in PostgreSQL result_cast_collation_name sql_identifier Applies to a feature not available in PostgreSQL result_cast_numeric_precision cardinal_number Applies to a feature not available in PostgreSQL result_cast_numeric_precision_radix cardinal_number Applies to a feature not available in PostgreSQL result_cast_numeric_scale cardinal_number Applies to a feature not available in PostgreSQL result_cast_datetime_precision character_data Applies to a feature not available in PostgreSQL result_cast_interval_type character_data Applies to a feature not available in PostgreSQL result_cast_interval_precision character_data Applies to a feature not available in PostgreSQL result_cast_type_udt_catalog sql_identifier Applies to a feature not available in PostgreSQL result_cast_type_udt_schema sql_identifier Applies to a feature not available in PostgreSQL result_cast_type_udt_name sql_identifier Applies to a feature not available in PostgreSQL result_cast_scope_catalog sql_identifier Applies to a feature not available in PostgreSQL result_cast_scope_schema sql_identifier Applies to a feature not available in PostgreSQL result_cast_scope_name sql_identifier Applies to a feature not available in PostgreSQL result_cast_maximum_cardinality cardinal_number Applies to a feature not available in PostgreSQL result_cast_dtd_identifier sql_identifier Applies to a feature not available in PostgreSQL The view schemata contains all schemas in the current database that are owned by a currently enabled role. Name Data Type Description catalog_name sql_identifier Name of the database that the schema is contained in (always the current database) schema_name sql_identifier Name of the schema schema_owner sql_identifier Name of the owner of the schema default_character_set_catalog sql_identifier Applies to a feature not available in PostgreSQL default_character_set_schema sql_identifier Applies to a feature not available in PostgreSQL default_character_set_name sql_identifier Applies to a feature not available in PostgreSQL sql_path character_data Applies to a feature not available in PostgreSQL The view sequences contains all sequences defined in the current database. Only those sequences are shown that the current user has access to (by way of being the owner or having some privilege). Name Data Type Description sequence_catalog sql_identifier Name of the database that contains the sequence (always the current database) sequence_schema sql_identifier Name of the schema that contains the sequence sequence_name sql_identifier Name of the sequence data_type character_data The data type of the sequence. In PostgreSQL, this is currently always bigint. numeric_precision cardinal_number This column contains the (declared or implicit) precision of the sequence data type (see above). The precision indicates the number of significant digits. It can be expressed in decimal (base 10) or binary (base 2) terms, as specified in the column numeric_precision_radix. numeric_precision_radix cardinal_number This column indicates in which base the values in the columns numeric_precision and numeric_scale are expressed. The value is either 2 or 10. numeric_scale cardinal_number This column contains the (declared or implicit) scale of the sequence data type (see above). The scale indicates the number of significant digits to the right of the decimal point. It can be expressed in decimal (base 10) or binary (base 2) terms, as specified in the column numeric_precision_radix. start_value character_data The start value of the sequence minimum_value character_data The minimum value of the sequence maximum_value character_data The maximum value of the sequence increment character_data The increment of the sequence cycle_option yes_or_no YES if the sequence cycles, else NO Note that in accordance with the SQL standard, the start, minimum, maximum, and increment values are returned as character strings. The table sql_features contains information about which formal features defined in the SQL standard are supported by PostgreSQL. This is the same information that is presented in . There you can also find some additional background information. Name Data Type Description feature_id character_data Identifier string of the feature feature_name character_data Descriptive name of the feature sub_feature_id character_data Identifier string of the subfeature, or a zero-length string if not a subfeature sub_feature_name character_data Descriptive name of the subfeature, or a zero-length string if not a subfeature is_supported yes_or_no YES if the feature is fully supported by the current version of PostgreSQL, NO if not is_verified_by character_data Always null, since the PostgreSQL development group does not perform formal testing of feature conformance comments character_data Possibly a comment about the supported status of the feature The table sql_implementation_info contains information about various aspects that are left implementation-defined by the SQL standard. This information is primarily intended for use in the context of the ODBC interface; users of other interfaces will probably find this information to be of little use. For this reason, the individual implementation information items are not described here; you will find them in the description of the ODBC interface. Name Data Type Description implementation_info_id character_data Identifier string of the implementation information item implementation_info_name character_data Descriptive name of the implementation information item integer_value cardinal_number Value of the implementation information item, or null if the value is contained in the column character_value character_value character_data Value of the implementation information item, or null if the value is contained in the column integer_value comments character_data Possibly a comment pertaining to the implementation information item The table sql_languages contains one row for each SQL language binding that is supported by PostgreSQL. PostgreSQL supports direct SQL and embedded SQL in C; that is all you will learn from this table. Name Data Type Description sql_language_source character_data The name of the source of the language definition; always ISO 9075, that is, the SQL standard sql_language_year character_data The year the standard referenced in sql_language_source was approved; currently 2003 sql_language_conformance character_data The standard conformance level for the language binding. For ISO 9075:2003 this is always CORE. sql_language_integrity character_data Always null (This value is relevant to an earlier version of the SQL standard.) sql_language_implementation character_data Always null sql_language_binding_style character_data The language binding style, either DIRECT or EMBEDDED sql_language_programming_language character_data The programming language, if the binding style is EMBEDDED, else null. PostgreSQL only supports the language C. The table sql_packages contains information about which feature packages defined in the SQL standard are supported by PostgreSQL. Refer to for background information on feature packages. Name Data Type Description feature_id character_data Identifier string of the package feature_name character_data Descriptive name of the package is_supported yes_or_no YES if the package is fully supported by the current version of PostgreSQL, NO if not is_verified_by character_data Always null, since the PostgreSQL development group does not perform formal testing of feature conformance comments character_data Possibly a comment about the supported status of the package The table sql_parts contains information about which of the several parts of the SQL standard are supported by PostgreSQL. Name Data Type Description feature_id character_data An identifier string containing the number of the part feature_name character_data Descriptive name of the part is_supported yes_or_no YES if the part is fully supported by the current version of PostgreSQL, NO if not is_verified_by character_data Always null, since the PostgreSQL development group does not perform formal testing of feature conformance comments character_data Possibly a comment about the supported status of the part The table sql_sizing contains information about various size limits and maximum values in PostgreSQL. This information is primarily intended for use in the context of the ODBC interface; users of other interfaces will probably find this information to be of little use. For this reason, the individual sizing items are not described here; you will find them in the description of the ODBC interface. Name Data Type Description sizing_id cardinal_number Identifier of the sizing item sizing_name character_data Descriptive name of the sizing item supported_value cardinal_number Value of the sizing item, or 0 if the size is unlimited or cannot be determined, or null if the features for which the sizing item is applicable are not supported comments character_data Possibly a comment pertaining to the sizing item The table sql_sizing_profiles contains information about the sql_sizing values that are required by various profiles of the SQL standard. PostgreSQL does not track any SQL profiles, so this table is empty. Name Data Type Description sizing_id cardinal_number Identifier of the sizing item sizing_name character_data Descriptive name of the sizing item profile_id character_data Identifier string of a profile required_value cardinal_number The value required by the SQL profile for the sizing item, or 0 if the profile places no limit on the sizing item, or null if the profile does not require any of the features for which the sizing item is applicable comments character_data Possibly a comment pertaining to the sizing item within the profile The view table_constraints contains all constraints belonging to tables that the current user owns or has some non-SELECT privilege on. Name Data Type Description constraint_catalog sql_identifier Name of the database that contains the constraint (always the current database) constraint_schema sql_identifier Name of the schema that contains the constraint constraint_name sql_identifier Name of the constraint table_catalog sql_identifier Name of the database that contains the table (always the current database) table_schema sql_identifier Name of the schema that contains the table table_name sql_identifier Name of the table constraint_type character_data Type of the constraint: CHECK, FOREIGN KEY, PRIMARY KEY, or UNIQUE is_deferrable yes_or_no YES if the constraint is deferrable, NO if not initially_deferred yes_or_no YES if the constraint is deferrable and initially deferred, NO if not The view table_privileges identifies all privileges granted on tables or views to a currently enabled role or by a currently enabled role. There is one row for each combination of table, grantor, and grantee. Name Data Type Description grantor sql_identifier Name of the role that granted the privilege grantee sql_identifier Name of the role that the privilege was granted to table_catalog sql_identifier Name of the database that contains the table (always the current database) table_schema sql_identifier Name of the schema that contains the table table_name sql_identifier Name of the table privilege_type character_data Type of the privilege: SELECT, INSERT, UPDATE, DELETE, TRUNCATE, REFERENCES, or TRIGGER is_grantable yes_or_no YES if the privilege is grantable, NO if not with_hierarchy yes_or_no Applies to a feature not available in PostgreSQL The view tables contains all tables and views defined in the current database. Only those tables and views are shown that the current user has access to (by way of being the owner or having some privilege). Name Data Type Description table_catalog sql_identifier Name of the database that contains the table (always the current database) table_schema sql_identifier Name of the schema that contains the table table_name sql_identifier Name of the table table_type character_data Type of the table: BASE TABLE for a persistent base table (the normal table type), VIEW for a view, FOREIGN TABLE for a foreign table, or LOCAL TEMPORARY for a temporary table self_referencing_column_name sql_identifier Applies to a feature not available in PostgreSQL reference_generation character_data Applies to a feature not available in PostgreSQL user_defined_type_catalog sql_identifier If the table is a typed table, the name of the database that contains the underlying data type (always the current database), else null. user_defined_type_schema sql_identifier If the table is a typed table, the name of the schema that contains the underlying data type, else null. user_defined_type_name sql_identifier If the table is a typed table, the name of the underlying data type, else null. is_insertable_into yes_or_no YES if the table is insertable into, NO if not (Base tables are always insertable into, views not necessarily.) is_typed yes_or_no YES if the table is a typed table, NO if not commit_action character_data If the table is a temporary table, then PRESERVE, else null. (The SQL standard defines other commit actions for temporary tables, which are not supported by PostgreSQL.) For triggers in the current database that specify a column list (like UPDATE OF column1, column2), the view triggered_update_columns identifies these columns. Triggers that do not specify a column list are not included in this view. Only those columns are shown that the current user owns or has some non-SELECT privilege on. Name Data Type Description trigger_catalog sql_identifier Name of the database that contains the trigger (always the current database) trigger_schema sql_identifier Name of the schema that contains the trigger trigger_name sql_identifier Name of the trigger event_object_catalog sql_identifier Name of the database that contains the table that the trigger is defined on (always the current database) event_object_schema sql_identifier Name of the schema that contains the table that the trigger is defined on event_object_table sql_identifier Name of the table that the trigger is defined on event_object_column sql_identifier Name of the column that the trigger is defined on The view triggers contains all triggers defined in the current database on tables and views that the current user owns or has some non-SELECT privilege on. Name Data Type Description trigger_catalog sql_identifier Name of the database that contains the trigger (always the current database) trigger_schema sql_identifier Name of the schema that contains the trigger trigger_name sql_identifier Name of the trigger event_manipulation character_data Event that fires the trigger (INSERT, UPDATE, or DELETE) event_object_catalog sql_identifier Name of the database that contains the table that the trigger is defined on (always the current database) event_object_schema sql_identifier Name of the schema that contains the table that the trigger is defined on event_object_table sql_identifier Name of the table that the trigger is defined on action_order cardinal_number Not yet implemented action_condition character_data WHEN condition of the trigger, null if none (also null if the table is not owned by a currently enabled role) action_statement character_data Statement that is executed by the trigger (currently always EXECUTE PROCEDURE function(...)) action_orientation character_data Identifies whether the trigger fires once for each processed row or once for each statement (ROW or STATEMENT) action_timing character_data Time at which the trigger fires (BEFORE, AFTER, or INSTEAD OF) action_reference_old_table sql_identifier Applies to a feature not available in PostgreSQL action_reference_new_table sql_identifier Applies to a feature not available in PostgreSQL action_reference_old_row sql_identifier Applies to a feature not available in PostgreSQL action_reference_new_row sql_identifier Applies to a feature not available in PostgreSQL created time_stamp Applies to a feature not available in PostgreSQL Triggers in PostgreSQL have two incompatibilities with the SQL standard that affect the representation in the information schema. First, trigger names are local to each table in PostgreSQL, rather than being independent schema objects. Therefore there can be duplicate trigger names defined in one schema, so long as they belong to different tables. (trigger_catalog and trigger_schema are really the values pertaining to the table that the trigger is defined on.) Second, triggers can be defined to fire on multiple events in PostgreSQL (e.g., ON INSERT OR UPDATE), whereas the SQL standard only allows one. If a trigger is defined to fire on multiple events, it is represented as multiple rows in the information schema, one for each type of event. As a consequence of these two issues, the primary key of the view triggers is really (trigger_catalog, trigger_schema, event_object_table, trigger_name, event_manipulation) instead of (trigger_catalog, trigger_schema, trigger_name), which is what the SQL standard specifies. Nonetheless, if you define your triggers in a manner that conforms with the SQL standard (trigger names unique in the schema and only one event type per trigger), this will not affect you. Prior to PostgreSQL 9.1, this view's columns action_timing, action_reference_old_table, action_reference_new_table, action_reference_old_row, and action_reference_new_row were named condition_timing, condition_reference_old_table, condition_reference_new_table, condition_reference_old_row, and condition_reference_new_row respectively. That was how they were named in the SQL:1999 standard. The new naming conforms to SQL:2003 and later. The view udt_privileges is intended to identify USAGE privileges granted on user-defined types to a currently enabled role or by a currently enabled role. Since data types do not have real privileges in PostgreSQL, this view shows implicit non-grantable USAGE privileges granted by the owner to PUBLIC for all types, including built-in ones (except domains, see for that). Name Data Type Description grantor sql_identifier Name of the role that granted the privilege grantee sql_identifier Name of the role that the privilege was granted to udt_catalog sql_identifier Name of the database containing the type (always the current database) udt_schema sql_identifier Name of the schema containing the type udt_name sql_identifier Name of the type privilege_type character_data Always TYPE USAGE is_grantable yes_or_no YES if the privilege is grantable, NO if not The view usage_privileges identifies USAGE privileges granted on various kinds of objects to a currently enabled role or by a currently enabled role. In PostgreSQL, this currently applies to collations, domains, foreign-data wrappers, and foreign servers. There is one row for each combination of object, grantor, and grantee. Since collations and domains do not have real privileges in PostgreSQL, this view shows implicit non-grantable USAGE privileges granted by the owner to PUBLIC for all collations and domains. The other object types, however, show real privileges. Name Data Type Description grantor sql_identifier Name of the role that granted the privilege grantee sql_identifier Name of the role that the privilege was granted to object_catalog sql_identifier Name of the database containing the object (always the current database) object_schema sql_identifier Name of the schema containing the object, if applicable, else an empty string object_name sql_identifier Name of the object object_type character_data COLLATION or DOMAIN or FOREIGN DATA WRAPPER or FOREIGN SERVER privilege_type character_data Always USAGE is_grantable yes_or_no YES if the privilege is grantable, NO if not The view user_defined_types currently contains all composite types defined in the current database. SQL knows about two kinds of user-defined types: structured types (also known as composite types in PostgreSQL) and distinct types (not implemented in PostgreSQL). To be future-proof, use the column user_defined_type_category to differentiate between these. Other user-defined types such as base types and enums, which are PostgreSQL extensions, are not shown here. For domains, see instead. Name Data Type Description user_defined_type_catalog sql_identifier Name of the database that contains the type (always the current database) user_defined_type_schema sql_identifier Name of the schema that contains the type user_defined_type_name sql_identifier Name of the type user_defined_type_category character_data Currently always STRUCTURED is_instantiable yes_or_no Applies to a feature not available in PostgreSQL is_final yes_or_no Applies to a feature not available in PostgreSQL ordering_form character_data Applies to a feature not available in PostgreSQL ordering_category character_data Applies to a feature not available in PostgreSQL ordering_routine_catalog sql_identifier Applies to a feature not available in PostgreSQL ordering_routine_schema sql_identifier Applies to a feature not available in PostgreSQL ordering_routine_name sql_identifier Applies to a feature not available in PostgreSQL reference_type character_data Applies to a feature not available in PostgreSQL data_type character_data Always USER-DEFINED TYPE (for joining against object_type columns in other views) character_maximum_length cardinal_number Applies to a feature not available in PostgreSQL character_octet_length cardinal_number Applies to a feature not available in PostgreSQL character_set_catalog sql_identifier Applies to a feature not available in PostgreSQL character_set_schema sql_identifier Applies to a feature not available in PostgreSQL character_set_name sql_identifier Applies to a feature not available in PostgreSQL collation_catalog sql_identifier Applies to a feature not available in PostgreSQL collation_schema sql_identifier Applies to a feature not available in PostgreSQL collation_name sql_identifier Applies to a feature not available in PostgreSQL numeric_precision cardinal_number Applies to a feature not available in PostgreSQL numeric_precision_radix cardinal_number Applies to a feature not available in PostgreSQL numeric_scale cardinal_number Applies to a feature not available in PostgreSQL datetime_precision cardinal_number Applies to a feature not available in PostgreSQL interval_type character_data Applies to a feature not available in PostgreSQL interval_precision character_data Applies to a feature not available in PostgreSQL source_dtd_identifier sql_identifier Applies to a feature not available in PostgreSQL ref_dtd_identifier sql_identifier Applies to a feature not available in PostgreSQL The view user_mapping_options contains all the options defined for user mappings in the current database. Only those user mappings are shown where the current user has access to the corresponding foreign server (by way of being the owner or having some privilege). Name Data Type Description authorization_identifier sql_identifier Name of the user being mapped, or PUBLIC if the mapping is public foreign_server_catalog sql_identifier Name of the database that the foreign server used by this mapping is defined in (always the current database) foreign_server_name sql_identifier Name of the foreign server used by this mapping option_name sql_identifier Name of an option option_value character_data Value of the option. This column will show as null unless the current user is the user being mapped, or the mapping is for PUBLIC and the current user is the server owner, or the current user is a superuser. The intent is to protect password information stored as user mapping option. The view user_mappings contains all user mappings defined in the current database. Only those user mappings are shown where the current user has access to the corresponding foreign server (by way of being the owner or having some privilege). Name Data Type Description authorization_identifier sql_identifier Name of the user being mapped, or PUBLIC if the mapping is public foreign_server_catalog sql_identifier Name of the database that the foreign server used by this mapping is defined in (always the current database) foreign_server_name sql_identifier Name of the foreign server used by this mapping The view view_column_usage identifies all columns that are used in the query expression of a view (the SELECT statement that defines the view). A column is only included if the table that contains the column is owned by a currently enabled role. Columns of system tables are not included. This should be fixed sometime. Name Data Type Description view_catalog sql_identifier Name of the database that contains the view (always the current database) view_schema sql_identifier Name of the schema that contains the view view_name sql_identifier Name of the view table_catalog sql_identifier Name of the database that contains the table that contains the column that is used by the view (always the current database) table_schema sql_identifier Name of the schema that contains the table that contains the column that is used by the view table_name sql_identifier Name of the table that contains the column that is used by the view column_name sql_identifier Name of the column that is used by the view The view view_routine_usage identifies all routines (functions and procedures) that are used in the query expression of a view (the SELECT statement that defines the view). A routine is only included if that routine is owned by a currently enabled role. Name Data Type Description table_catalog sql_identifier Name of the database containing the view (always the current database) table_schema sql_identifier Name of the schema containing the view table_name sql_identifier Name of the view specific_catalog sql_identifier Name of the database containing the function (always the current database) specific_schema sql_identifier Name of the schema containing the function specific_name sql_identifier The specific name of the function. See for more information. The view view_table_usage identifies all tables that are used in the query expression of a view (the SELECT statement that defines the view). A table is only included if that table is owned by a currently enabled role. System tables are not included. This should be fixed sometime. Name Data Type Description view_catalog sql_identifier Name of the database that contains the view (always the current database) view_schema sql_identifier Name of the schema that contains the view view_name sql_identifier Name of the view table_catalog sql_identifier Name of the database that contains the table that is used by the view (always the current database) table_schema sql_identifier Name of the schema that contains the table that is used by the view table_name sql_identifier Name of the table that is used by the view The view views contains all views defined in the current database. Only those views are shown that the current user has access to (by way of being the owner or having some privilege). Name Data Type Description table_catalog sql_identifier Name of the database that contains the view (always the current database) table_schema sql_identifier Name of the schema that contains the view table_name sql_identifier Name of the view view_definition character_data Query expression defining the view (null if the view is not owned by a currently enabled role) check_option character_data Applies to a feature not available in PostgreSQL is_updatable yes_or_no YES if the view is updatable (allows UPDATE and DELETE), NO if not is_insertable_into yes_or_no YES if the view is insertable into (allows INSERT), NO if not is_trigger_updatable yes_or_no YES if the view has an INSTEAD OF UPDATE trigger defined on it, NO if not is_trigger_deletable yes_or_no YES if the view has an INSTEAD OF DELETE trigger defined on it, NO if not is_trigger_insertable_into yes_or_no YES if the view has an INSTEAD OF INSERT trigger defined on it, NO if not