postgresql - PostgreSQL 数据中 `pg_logical` 目录的用途是什么？

Question

我刚刚在测试我设置的 PostgreSQL 9.4 集群的故障转移时偶然发现了这个错误。在这里，我试图将一个奴隶提升为新的主人:

$ repmgr -f /etc/repmgr/repmgr.conf --verbose standby promote

2014-09-22 10:46:37 UTC LOG:  database system shutdown was interrupted; last known up at 2014-09-22 10:44:02 UTC
2014-09-22 10:46:37 UTC LOG:  database system was not properly shut down; automatic recovery in progress
2014-09-22 10:46:37 UTC LOG:  redo starts at 0/18000028
2014-09-22 10:46:37 UTC LOG:  consistent recovery state reached at 0/19000600
2014-09-22 10:46:37 UTC LOG:  record with zero length at 0/1A000090
2014-09-22 10:46:37 UTC LOG:  redo done at 0/1A000028
2014-09-22 10:46:37 UTC LOG:  last completed transaction was at log time 2014-09-22 10:36:22.679806+00
2014-09-22 10:46:37 UTC FATAL:  could not open directory "pg_logical/snapshots": No such file or directory
2014-09-22 10:46:37 UTC LOG:  startup process (PID 2595) exited with exit code 1
2014-09-22 10:46:37 UTC LOG:  aborting startup due to startup process failure

pg_logical/snapshots 目录实际上存在于主节点上并且它是空的。

UPD:我刚刚手动创建了空目录 pg_logical/snapshots 和 pg_logical/mappings 并且服务器已正常启动。 repmgr standby clone 似乎在同步时忽略了这个目录。但问题仍然存在，因为我只是好奇这个目录是做什么用的，也许我在我的设置中遗漏了一些东西。简单地谷歌搜索它没有产生任何有意义的结果。

Answer 1

它用于 new logical changeset extraction / logical replication feature in 9.4 .

虽然这不应该发生......它表明某处存在重大错误，可能是 repmgr。我会等待详细信息(repmgr 版本等)。

更新:确认，it's a repmgr bug .它已经在 git master 中修复(并且在本报告之前)并将在下一个版本中。考虑到这个问题的重要性，最好尽快。