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Add new to_reg* functions for error-free OID lookups.

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These functions won't throw an error if the object doesn't exist,
or if (for functions and operators) there's more than one matching
object.

Yugo Nagata and Nozomi Anzai, reviewed by Amit Khandekar, Marti
Raudsepp, Amit Kapila, and me.
This commit is contained in:
Robert Haas
2014-04-08 10:27:56 -04:00
parent 7ca32e255b
commit 0886fc6a5c
18 changed files with 457 additions and 19 deletions
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48
doc/src/sgml/func.sgml
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@ -15279,6 +15279,22 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
<primary>collation for</primary>
</indexterm>
<indexterm>
<primary>to_regclass</primary>
</indexterm>
<indexterm>
<primary>to_regproc</primary>
</indexterm>
<indexterm>
<primary>to_regoper</primary>
</indexterm>
<indexterm>
<primary>to_regtype</primary>
</indexterm>
<para>
<xref linkend="functions-info-catalog-table"> lists functions that
extract information from the system catalogs.
@ -15449,6 +15465,26 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
<entry><type>text</type></entry>
<entry>get the collation of the argument</entry>
</row>
<row>
<entry><literal><function>to_regclass(<parameter>rel_name</parameter>)</function></literal></entry>
<entry><type>regclass</type></entry>
<entry>get the oid of the named relation</entry>
</row>
<row>
<entry><literal><function>to_regproc(<parameter>func_name</parameter>)</function></literal></entry>
<entry><type>regproc</type></entry>
<entry>get the oid of the named function</entry>
</row>
<row>
<entry><literal><function>to_regoper(<parameter>operator_name</parameter>)</function></literal></entry>
<entry><type>regoper</type></entry>
<entry>get the oid of the named operator</entry>
</row>
<row>
<entry><literal><function>to_regtype(<parameter>type_name</parameter>)</function></literal></entry>
<entry><type>regtype</type></entry>
<entry>get the oid of the named type</entry>
</row>
</tbody>
</tgroup>
</table>
@ -15614,6 +15650,18 @@ SELECT collation for ('foo' COLLATE "de_DE");
is not of a collatable data type, then an error is raised.
</para>
<para>
The <function>to_regclass</function>, <function>to_regproc</function>,
<function>to_regoper</function> and <function>to_regtype</function>
translate relation, function, operator, and type names to objects of
type <type>regclass</>, <type>regproc</>, <type>regoper</> and
<type>regtype</>, respectively. These functions differ from a cast from
text in that they don't accept a numeric OID, and that they return null
rather than throwing an error if the name is not found (or, for
<function>to_regproc</function> and <function>to_regoper</function>, if
the given name matches multiple objects).
</para>
<indexterm>
<primary>col_description</primary>
</indexterm>