<primary>format_type</primary>

</indexterm>

<indexterm>

<primary>pg_describe_object</primary>

</indexterm>

<indexterm>

<primary>pg_identify_object</primary>

</indexterm>

<indexterm>

<primary>pg_get_constraintdef</primary>

</indexterm>

<entry><type>text</type></entry>

<entry>get SQL name of a data type</entry>

</row>

<row>

<entry><literal><function>pg_describe_object(<parameter>catalog_id</parameter>, <parameter>object_id</parameter>, <parameter>object_sub_id</parameter>)</function></literal></entry>

<entry><type>text</type></entry>

<entry>get description of a database object</entry>

</row>

<row>

<entry><literal><function>pg_identify_object(<parameter>catalog_id</parameter> <type>oid</>, <parameter>object_id</parameter> <type>oid</>, <parameter>object_sub_id</parameter> <type>integer</>)</function></literal></entry>

<entry><parameter>type</> <type>text</>, <parameter>schema</> <type>text</>, <parameter>name</> <type>text</>, <parameter>identity</> <type>text</></entry>

<entry>get identity of a database object</entry>

</row>

<row>

<entry><literal><function>pg_get_constraintdef(<parameter>constraint_oid</parameter>)</function></literal></entry>

<entry><type>text</type></entry>

<structname>pg_class</> catalogs.

</para>

<para>

<function>pg_describe_object</function> returns a textual description of a database

object specified by catalog OID, object OID and a (possibly zero) sub-object ID.

This description is intended to be human-readable, and might be translated,

depending on server configuration.

This is useful to determine the identity of an object as stored in the

<structname>pg_depend</structname> catalog.

</para>

<para>

<function>pg_identify_object</function> returns a row containing enough information

to uniquely identify the database object specified by catalog OID, object OID and a

(possibly zero) sub-object ID. This information is intended to be machine-readable,

and is never translated.

<parameter>type</> identifies the type of database object;

<parameter>schema</> is the schema name that the object belongs in, or

<literal>NULL</> for object types that do not belong to schemas;

<parameter>name</> is the name of the object, quoted if necessary, only

present if it can be used (alongside schema name, if pertinent) as a unique

identifier of the object, otherwise <literal>NULL</>;

<parameter>identity</> is the complete object identity, with the precise format

depending on object type, and each part within the format being

schema-qualified and quoted as necessary.

</para>

<para>

<function>pg_typeof</function> returns the OID of the data type of the

value that is passed to it. This can be helpful for troubleshooting or

the given name matches multiple objects).

</para>

<indexterm>

<primary>pg_describe_object</primary>

</indexterm>

<indexterm>

<primary>pg_identify_object</primary>

</indexterm>

<indexterm>

<primary>pg_identify_object_as_address</primary>

</indexterm>

<indexterm>

<primary>pg_get_object_address</primary>

</indexterm>

<para>

<xref linkend="functions-info-object-table"> lists functions related to

database object identification and addressing.

</para>

<table id="functions-info-object-table">

<title>Object Information and Addressing Functions</title>

<tgroup cols="3">

<thead>

<row><entry>Name</entry> <entry>Return Type</entry> <entry>Description</entry></row>

</thead>

<tbody>

<row>

<entry><literal><function>pg_describe_object(<parameter>catalog_id</parameter>, <parameter>object_id</parameter>, <parameter>object_sub_id</parameter>)</function></literal></entry>

<entry><type>text</type></entry>

<entry>get description of a database object</entry>

</row>

<row>

<entry><literal><function>pg_identify_object(<parameter>catalog_id</parameter> <type>oid</>, <parameter>object_id</parameter> <type>oid</>, <parameter>object_sub_id</parameter> <type>integer</>)</function></literal></entry>

<entry><parameter>type</> <type>text</>, <parameter>schema</> <type>text</>, <parameter>name</> <type>text</>, <parameter>identity</> <type>text</></entry>

<entry>get identity of a database object</entry>

</row>

<row>

<entry><literal><function>pg_identify_object_as_address(<parameter>catalog_id</parameter> <type>oid</>, <parameter>object_id</parameter> <type>oid</>, <parameter>object_sub_id</parameter> <type>integer</>)</function></literal></entry>

<entry><parameter>type</> <type>text</>, <parameter>name</> <type>text[]</>, <parameter>args</> <type>text[]</></entry>

<entry>get external representation of a database object's address</entry>

</row>

<row>

<entry><literal><function>pg_get_object_address(<parameter>type</parameter> <type>text</>, <parameter>name</parameter> <type>text[]</>, <parameter>args</parameter> <type>text[]</>)</function></literal></entry>

<entry><parameter>catalog_id</> <type>oid</>, <parameter>object_id</> <type>oid</>, <parameter>object_sub_id</> <type>int32</></entry>

<entry>get address of a database object, from its external representation</entry>

</row>

</tbody>

</tgroup>

</table>

<para>

<function>pg_describe_object</function> returns a textual description of a database

object specified by catalog OID, object OID and a (possibly zero) sub-object ID.

This description is intended to be human-readable, and might be translated,

depending on server configuration.

This is useful to determine the identity of an object as stored in the

<structname>pg_depend</structname> catalog.

</para>

<para>

<function>pg_identify_object</function> returns a row containing enough information

to uniquely identify the database object specified by catalog OID, object OID and a

(possibly zero) sub-object ID. This information is intended to be machine-readable,

and is never translated.

<parameter>type</> identifies the type of database object;

<parameter>schema</> is the schema name that the object belongs in, or

<literal>NULL</> for object types that do not belong to schemas;

<parameter>name</> is the name of the object, quoted if necessary, only

present if it can be used (alongside schema name, if pertinent) as a unique

identifier of the object, otherwise <literal>NULL</>;

<parameter>identity</> is the complete object identity, with the precise format

depending on object type, and each part within the format being

schema-qualified and quoted as necessary.

</para>

<para>

<function>pg_identify_object_as_address</function> returns a row containing

enough information to uniquely identify the database object specified by

catalog OID, object OID and a (possibly zero) sub-object ID. The returned

information is independent of the current server, that is, it could be used

to identify an identically named object in another server.

<parameter>type</> identifies the type of database object;

<parameter>name</> and <parameter>args</> are text arrays that together

form a reference to the object. These three columns can be passed to

<function>pg_get_object_address</> to obtain the internal address

of the object.

This function is the inverse of <function>pg_get_object_address</function>.

</para>

<para>

<function>pg_get_object_address</function> returns a row containing enough

information to uniquely identify the database object specified by its

type and object name and argument arrays. The returned values are the

ones that would be used in system catalogs such as <structname>pg_depend</>

and can be passed to other system functions such as

<function>pg_identify_object</> or <function>pg_describe_object</>.

<parameter>catalog_id</> is the OID of the system catalog containing the

object;

<parameter>object_id</> is the OID of the object itself, and

<parameter>object_sub_id</> is the object sub-ID, or zero if none.

This function is the inverse of <function>pg_identify_object_as_address</function>.

</para>

<indexterm>

<primary>col_description</primary>

</indexterm>