PHP实战中知识总结 / PgSQL - pg_available_extensions（系统表）
pg_available_extensions视图列出了可用于安装的扩展
| 列 | 类型 | 描述 |
|---|---|---|
| name | name | 扩展名 |
| default_version | text | 默认版本 |
| installed_version | text | 当前已安装的扩展版本，如果没有安装则为NULL |
| comment | text | 扩展的控制文件的注释字符串 |
postgres=# SELECT * from pg_available_extensions;
name | default_version | installed_version | comment
--------------------+-----------------+-------------------+------------------------------------------------------------------------
pg_stat_statements | 1.8 | 1.8 | track planning and execution statistics of all SQL statements executed
first_last_agg | 0.1.4 | 0.1.4 | first() and last() aggregate functions
plpgsql | 1.0 | 1.0 | PL/pgSQL procedural language
pg_freespacemap | 1.2 | 1.2 | examine the free space map (FSM)
pg_visibility | 1.2 | 1.2 | examine the visibility map (VM) and page-level visibility info
plpython2u | 1.0 | | PL/Python2U untrusted procedural language
plperl | 1.0 | | PL/Perl procedural language
demo | 1.0 | 1.0 | A key/value pair data type
plperlu | 1.0 | | PL/PerlU untrusted procedural language
pg_trgm | 1.5 | 1.5 | text similarity measurement and index searching based on trigrams
plpythonu | 1.0 | | PL/PythonU untrusted procedural language
(11 rows)