The Information Schema
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.
The Schema
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 this 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.
Data Types
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
Every column in the information schema has one of these four types.
Boolean (true/false) data is represented in the information schema
by a column of type character_data that contains
either YES or NO. (The
information schema was invented before the type
boolean was added to the SQL standard, so this
convention is necessary to keep the information schema backward
compatible.)
information_schema_catalog_name
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).
information_schema_catalog_name Columns
Name
Data Type
Description
catalog_name
sql_identifier
Name of the database that contains this information schema
applicable_roles
The view applicable_roles identifies all groups
that the current user is a member of. (A role is the same thing as
a group.) Generally, it is better to use the view
enabled_roles instead of this one; see also
there.
applicable_roles Columns
Name
Data Type
Description
grantee
sql_identifier
Always the name of the current user
role_name
sql_identifier
Name of a group
is_grantable
character_data
Applies to a feature not available in PostgreSQL
check_constraints
The view check_constraints contains all check
constraints, either defined on a table or on a domain, that are
owned by the current user. (The owner of the table or domain is
the owner of the constraint.)
check_constraints Columns
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
column_domain_usage
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 the current user.
column_domain_usage Columns
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
column_privileges
The view column_privileges identifies all
privileges granted on columns to the current user or by the current
user. There is one row for each combination of column, grantor,
and grantee. Privileges granted to groups are identified in the
view role_column_grants.
In PostgreSQL, you can only grant
privileges on entire tables, not individual columns. Therefore,
this view contains the same information as
table_privileges, just represented through one
row for each column in each appropriate table, but it only covers
privilege types where column granularity is possible:
SELECT, INSERT,
UPDATE, REFERENCES. If you
want to make your applications fit for possible future
developments, it is generally the right choice to use this view
instead of table_privileges if one of those
privilege types is concerned.
column_privileges Columns
Name
Data Type
Description
grantor
sql_identifier
Name of the user that granted the privilege
grantee
sql_identifier
Name of the user or group 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
character_data
YES if the privilege is grantable, NO if not
Note that the column grantee makes no
distinction between users and groups. If you have users and groups
with the same name, there is unfortunately no way to distinguish
them. A future version of PostgreSQL
will possibly prohibit having users and groups with the same name.
column_udt_usage
The view column_udt_usage identifies all columns
that use data types owned by the current user. Note that in
PostgreSQL, built-in data types behave
like user-defined types, so they are included here as well. See
also for details.
column_udt_usage Columns
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
columns
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).
columns Columns
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 (null if the current user is
not the owner of the table containing the column)
is_nullable
character_data
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 may 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 (this
should not be of concern to PostgreSQL users); null for all
other data types.
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 may 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 may
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, or
interval type, the declared precision; null for all other data
types or if no precision was declared.
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
character_data
Applies to a feature not available in PostgreSQL
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 may 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.
constraint_column_usage
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
the current user. 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.
constraint_column_usage 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
constraint_table_usage
The view constraint_table_usage identifies all
tables in the current database that are used by some constraint and
are owned by the current user. (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.
constraint_table_usage Columns
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
data_type_privileges
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
descriptors 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.
domain_constraints Columns
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.
domain_constraints
The view domain_constraints contains all
constraints belonging to domains owned by the current user.
domain_constraints Columns
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
character_data
YES if the constraint is deferrable, NO if not
initially_deferred
character_data
YES if the constraint is deferrable and initially deferred, NO if not
domain_udt_usage
The view domain_udt_usage identifies all columns
that use data types owned by the current user. Note that in
PostgreSQL, built-in data types behave
like user-defined types, so they are included here as well.
domain_udt_usage Columns
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
domains
The view domains contains all domains defined in
the current database.
domains Columns
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 (this should not be of concern to
PostgreSQL users); null for all
other data types.
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 column.
The precision indicates the number of significant digits. It
may 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 column.
The scale indicates the number of significant digits to the
right of the decimal point. It may 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 the domain has a date, time, or interval type, the declared
precision; null for all other data types or if no precision was
declared.
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.)
element_types
The view element_types contains the data type
descriptors of the elements of arrays. When a table column,
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.array_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.
element_types Columns
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), DOMAIN (the array is used by
that domain), ROUTINE (the array is used by
a parameter or the return data type of that function).
array_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.
enabled_roles
The view enabled_roles identifies all groups
that the current user is a member of. (A role is the same thing as
a group.) The difference between this view and
applicable_roles is that in the future there may
be a mechanism to enable and disable groups during a session. In
that case this view identifies those groups that are currently
enabled.
enabled_roles Columns
Name
Data Type
Description
role_name
sql_identifier
Name of a group
key_column_usage
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 are contained in a
table owned the current user.
key_column_usage Columns
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 some 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 some constraint
table_name
sql_identifier
Name of the table that contains the column that is restricted
by some constraint
column_name
sql_identifier
Name of the column that is restricted by some constraint
ordinal_position
cardinal_number
Ordinal position of the column within the constraint key (count
starts at 1)
parameters
The view parameters contains information about
the parameters (arguments) 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).
parameters Columns
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
Always IN, meaning input parameter (In the
future there might be other parameter modes.)
is_result
character_data
Applies to a feature not available in PostgreSQL
as_locator
character_data
Applies to a feature not available in PostgreSQL
parameter_name
sql_identifier
Always null, since PostgreSQL does not support named parameters
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.)
referential_constraints
The view referential_constraints contains all
referential (foreign key) constraints in the current database that
belong to a table owned by the current user.
referential_constraints Columns
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.
role_column_grants
The view role_column_grants identifies all
privileges granted on columns to a group that the current user is a
member of. Further information can be found under
column_privileges.
role_column_grants Columns
Name
Data Type
Description
grantor
sql_identifier
Name of the user that granted the privilege
grantee
sql_identifier
Name of the group 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
character_data
YES if the privilege is grantable, NO if not
role_routine_grants
The view role_routine_grants identifies all
privileges granted on functions to a group that the current user is
a member of. Further information can be found under
routine_privileges.
role_routine_grants Columns
Name
Data Type
Description
grantor
sql_identifier
Name of the user that granted the privilege
grantee
sql_identifier
Name of the group 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 (may be duplicated in case of overloading)
privilege_type
character_data
Always EXECUTE (the only privilege type for functions)
is_grantable
character_data
YES if the privilege is grantable, NO if not
role_table_grants
The view role_table_grants identifies all
privileges granted on tables or views to a group that the current
user is a member of. Further information can be found under
table_privileges.
role_table_grants Columns
Name
Data Type
Description
grantor
sql_identifier
Name of the user that granted the privilege
grantee
sql_identifier
Name of the group 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,
DELETE, INSERT,
UPDATE, REFERENCES,
RULE, or TRIGGER
is_grantable
character_data
YES if the privilege is grantable, NO if not
with_hierarchy
character_data
Applies to a feature not available in PostgreSQL
role_usage_grants
The view role_usage_grants is meant to identify
USAGE privileges granted on various kinds of
objects to a group that the current user is a member of. In
PostgreSQL, this currently only applies
to domains, and since domains do not have real privileges in
PostgreSQL, this view is empty. Further
information can be found under usage_privileges.
In the future, this view may contain more useful information.
role_usage_grants Columns
Name
Data Type
Description
grantor
sql_identifier
In the future, the name of the user that granted the privilege
grantee
sql_identifier
In the future, the name of the group 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
object_name
sql_identifier
Name of the object
object_type
character_data
In the future, the type of the object
privilege_type
character_data
Always USAGE
is_grantable
character_data
YES if the privilege is grantable, NO if not
routine_privileges
The view routine_privileges identifies all
privileges granted on functions to the current user or by the
current user. There is one row for each combination of function,
grantor, and grantee. Privileges granted to groups are identified
in the view role_routine_grants.
routine_privileges Columns
Name
Data Type
Description
grantor
sql_identifier
Name of the user that granted the privilege
grantee
sql_identifier
Name of the user or group 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 (may be duplicated in case of overloading)
privilege_type
character_data
Always EXECUTE (the only privilege type for functions)
is_grantable
character_data
YES if the privilege is grantable, NO if not
Note that the column grantee makes no
distinction between users and groups. If you have users and groups
with the same name, there is unfortunately no way to distinguish
them. A future version of PostgreSQL
will possibly prohibit having users and groups with the same name.
routines
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).
routines Columns
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 (may 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 current user is
not the owner of the function). (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
character_data
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
character_data
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
character_data
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
character_data
Applies to a feature not available in PostgreSQL
is_implicitly_invocable
character_data
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
character_data
Applies to a feature not available in PostgreSQL
schemata
The view schemata contains all schemas in the
current database that are owned by the current user.
schemata Columns
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
sql_features
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.
sql_features Columns
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
character_data
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
sql_implementation_info
The table sql_information_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.
sql_implementation_info Columns
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
sql_languages
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.
sql_languages Columns
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
1999>
sql_language_comformance
character_data
The standard conformance level for the language binding. For
ISO 9075:1999 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.
sql_packages
The table sql_packages contains information
about which features packages defined in the SQL standard are
supported by PostgreSQL. Refer to for background information on feature packages.
sql_packages Columns
Name
Data Type
Description
feature_id
character_data
Identifier string of the package
feature_name
character_data
Descriptive name of the package
is_supported
character_data
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
sql_sizing
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.
sql_sizing Columns
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
sql_sizing_profiles
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.
sql_sizing_profiles Columns
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
table_constraints
The view table_constraints contains all
constraints belonging to tables owned by the current user.
table_constraints Columns
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
character_data
YES if the constraint is deferrable, NO if not
initially_deferred
character_data
YES if the constraint is deferrable and initially deferred, NO if not
table_privileges
The view table_privileges identifies all
privileges granted on tables or views to the current user or by the
current user. There is one row for each combination of table,
grantor, and grantee. Privileges granted to groups are identified
in the view role_table_grants.
table_privileges Columns
Name
Data Type
Description
grantor
sql_identifier
Name of the user that granted the privilege
grantee
sql_identifier
Name of the user or group 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,
DELETE, INSERT,
UPDATE, REFERENCES,
RULE, or TRIGGER
is_grantable
character_data
YES if the privilege is grantable, NO if not
with_hierarchy
character_data
Applies to a feature not available in PostgreSQL
Note that the column grantee makes no
distinction between users and groups. If you have users and groups
with the same name, there is unfortunately no way to distinguish
them. A future version of PostgreSQL
will possibly prohibit having users and groups with the same name.
tables
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).
tables Columns
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, 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
Applies to a feature not available in PostgreSQL
user_defined_type_schema
sql_identifier
Applies to a feature not available in PostgreSQL
user_defined_type_name
sql_identifier
Applies to a feature not available in PostgreSQL
triggers
The view triggers contains all triggers defined
in the current database that are owned by the current user. (The
owner of the table is the owner of the trigger.)
triggers Columns
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_name
sql_identifier
Name of the table that the trigger is defined on
action_order
cardinal_number
Not yet implemented
action_condition
character_data
Applies to a feature not available in PostgreSQL
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)
condition_timing
character_data
Time at which the trigger fires (BEFORE or
AFTER)
condition_reference_old_table
sql_identifier
Applies to a feature not available in PostgreSQL
condition_reference_new_table
sql_identifier
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 the table in PostgreSQL, rather
than independent schema objects. Therefore there may be duplicate
trigger names defined in one schema, as 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, trigger_name,
event_object_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.
usage_privileges
The view usage_privileges is meant to identify
USAGE privileges granted on various kinds of
objects to the current user or by the current user. In
PostgreSQL, this currently only applies
to domains, and since domains do not have real privileges in
PostgreSQL, this view shows implicit
USAGE privileges granted to
PUBLIC for all domains. In the future, this
view may contain more useful information.
usage_privileges Columns
Name
Data Type
Description
grantor
sql_identifier
Currently set to the name of the owner of the object
grantee
sql_identifier
Currently always PUBLIC
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
object_name
sql_identifier
Name of the object
object_type
character_data
Currently always DOMAIN
privilege_type
character_data
Always USAGE
is_grantable
character_data
Currently always NO
view_column_usage
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 current user is the owner of the
table that contains the column.
Columns of system tables are not included. This should be fixed
sometime.
view_column_usage Columns
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
view_table_usage
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 the current user is the owner of that
table.
System tables are not included. This should be fixed sometime.
view_table_usage Columns
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 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
views
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).
views Columns
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 current user is
not the owner of the view)
check_option
character_data
Applies to a feature not available in PostgreSQL
is_updatable
character_data
Not yet implemented
is_insertable_into
character_data
Not yet implemented