pg_logicalinspect 模块提供 SQL 函数，允许你检查逻辑解码组件的内容。它可以检查运行中的 PostgreSQL 数据库集簇的序列化逻辑快照，这对调试或教学很有用。
默认情况下，这些函数的使用仅限于超级用户和 pg_read_server_files 角色的成员。超级用户可以通过 GRANT 将访问权限授予其他用户。
pg_get_logical_snapshot_meta(filename text) returns record
#
获取位于服务器 pg_logical/snapshots 目录中快照文件的逻辑快照元数据。filename 参数表示快照文件名。例如：
postgres=# SELECT * FROM pg_ls_logicalsnapdir();
-[ RECORD 1 ]+-----------------------
name | 0-40796E18.snap
size | 152
modification | 2024-08-14 16:36:32+00
postgres=# SELECT * FROM pg_get_logical_snapshot_meta('0-40796E18.snap');
-[ RECORD 1 ]--------
magic | 1369563137
checksum | 1028045905
version | 6
postgres=# SELECT ss.name, meta.* FROM pg_ls_logicalsnapdir() AS ss,
pg_get_logical_snapshot_meta(ss.name) AS meta;
-[ RECORD 1 ]-------------
name | 0-40796E18.snap
magic | 1369563137
checksum | 1028045905
version | 6
如果 filename 与任何快照文件都不匹配，该函数将抛出错误。
pg_get_logical_snapshot_info(filename text) returns record
#
获取位于服务器 pg_logical/snapshots 目录中快照文件的逻辑快照信息。filename 参数表示快照文件名。例如：
postgres=# SELECT * FROM pg_ls_logicalsnapdir();
-[ RECORD 1 ]+-----------------------
name | 0-40796E18.snap
size | 152
modification | 2024-08-14 16:36:32+00
postgres=# SELECT * FROM pg_get_logical_snapshot_info('0-40796E18.snap');
-[ RECORD 1 ]------------+-----------
state | consistent
xmin | 751
xmax | 751
start_decoding_at | 0/40796AF8
two_phase_at | 0/40796AF8
initial_xmin_horizon | 0
building_full_snapshot | f
in_slot_creation | f
last_serialized_snapshot | 0/0
next_phase_at | 0
committed_count | 0
committed_xip |
catchange_count | 2
catchange_xip | {751,752}
postgres=# SELECT ss.name, info.* FROM pg_ls_logicalsnapdir() AS ss,
pg_get_logical_snapshot_info(ss.name) AS info;
-[ RECORD 1 ]------------+----------------
name | 0-40796E18.snap
state | consistent
xmin | 751
xmax | 751
start_decoding_at | 0/40796AF8
two_phase_at | 0/40796AF8
initial_xmin_horizon | 0
building_full_snapshot | f
in_slot_creation | f
last_serialized_snapshot | 0/0
next_phase_at | 0
committed_count | 0
committed_xip |
catchange_count | 2
catchange_xip | {751,752}
如果 filename 与任何快照文件都不匹配，该函数将抛出错误。
Bertrand Drouvot <bertranddrouvot.pg@gmail.com>