The catalog pg_pltemplate stores "template" information for procedural languages. A template for a language allows the language to be created in a particular database by a simple CREATE LANGUAGE command, with no need to specify implementation details.
Unlike most system catalogs, pg_pltemplate is shared across all databases of a cluster: there is only one copy of pg_pltemplate per cluster, not one per database. This allows the information to be accessible in each database as it is needed.
Table 50-36. pg_pltemplate Columns
|tmplname||name||Name of the language this template is for|
|tmpltrusted||boolean||True if language is considered trusted|
|tmpldbacreate||boolean||True if language may be created by a database owner|
|tmplhandler||text||Name of call handler function|
|tmplinline||text||Name of anonymous-block handler function, or null if none|
|tmplvalidator||text||Name of validator function, or null if none|
|tmpllibrary||text||Path of shared library that implements language|
|tmplacl||aclitem||Access privileges for template (not actually used)|
There are not currently any commands that manipulate procedural language templates; to change the built-in information, a superuser must modify the table using ordinary INSERT, DELETE, or UPDATE commands.
Note: It is likely that pg_pltemplate will be removed in some future release of PostgreSQL, in favor of keeping this knowledge about procedural languages in their respective extension installation scripts.