PHP实战中知识总结 / PgSQL - pg_available_extension_versions（系统表）
pg_available_extension_versions视图列出了可用于安装的指定扩展版本
| 列 | 类型 | 描述 |
|---|---|---|
| name | name | 扩展名 |
| version | text | 默认版本 |
| installed | bool | 如果此版本的扩展当前已安装则为真 |
| superuser | bool | 如果只有超级用户被允许安装此扩展则为真(更多请参见trusted) |
| trusted | bool | 如果扩展可以由具有适当权限的非超级用户安装，则为真 |
| relocatable | bool | 如果扩展能被重定位到另一个模式则为真 |
| schema | name | 此扩展必须被安装到的模式名，如果此扩展是部分或者全部可以重定位的，此列为NULL |
| requires | name[] | 要引入的扩展名称，没有则为NULL |
| comment | text | 扩展的控制文件的注释字符串 |
postgres=# select * from pg_available_extension_versions;
name | version | installed | superuser | trusted | relocatable | schema | requires | comment
--------------------+---------+-----------+-----------+---------+-------------+------------+----------+------------------------------------------------------------------------
pg_stat_statements | 1.4 | f | t | f | t | | | track planning and execution statistics of all SQL statements executed
pg_stat_statements | 1.5 | f | t | f | t | | | track planning and execution statistics of all SQL statements executed
pg_stat_statements | 1.6 | f | t | f | t | | | track planning and execution statistics of all SQL statements executed
pg_stat_statements | 1.7 | f | t | f | t | | | track planning and execution statistics of all SQL statements executed
pg_stat_statements | 1.8 | t | t | f | t | | | track planning and execution statistics of all SQL statements executed
first_last_agg | 0.1.4 | t | t | f | t | | | first() and last() aggregate functions
plpgsql | 1.0 | t | t | t | f | pg_catalog | | PL/pgSQL procedural language
pg_freespacemap | 1.1 | f | t | f | t | | | examine the free space map (FSM)
pg_freespacemap | 1.2 | t | t | f | t | | | examine the free space map (FSM)
pg_visibility | 1.1 | f | t | f | t | | | examine the visibility map (VM) and page-level visibility info
pg_visibility | 1.2 | t | t | f | t | | | examine the visibility map (VM) and page-level visibility info
plpython2u | 1.0 | f | t | f | f | pg_catalog | | PL/Python2U untrusted procedural language
plperl | 1.0 | f | t | t | f | pg_catalog | | PL/Perl procedural language
demo | 1.0 | t | t | f | f | | | A key/value pair data type
plperlu | 1.0 | f | t | f | f | pg_catalog | | PL/PerlU untrusted procedural language
pg_trgm | 1.3 | f | t | t | t | | | text similarity measurement and index searching based on trigrams
pg_trgm | 1.4 | f | t | t | t | | | text similarity measurement and index searching based on trigrams
pg_trgm | 1.5 | t | t | t | t | | | text similarity measurement and index searching based on trigrams
plpythonu | 1.0 | f | t | f | f | pg_catalog | | PL/PythonU untrusted procedural language
(19 rows)