PostgreSQL 10.0 preview 变化 - pg_xlog,pg_clog,pg_log目录更名为pg_wal,pg_xact,log

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10.0 把几个有一定“歧义”的目录更名了。它们分别为

pg_xlog, pg_clog, pg_log


pg_wal, pg_xact, log

分别对应WAL(write ahead log)日志,事务状态日志,日志。



Rename "pg_xlog" directory to "pg_wal".  
author	Robert Haas <>	  
Thu, 20 Oct 2016 23:24:37 +0800 (11:24 -0400)  
committer	Robert Haas <>	  
Thu, 20 Oct 2016 23:32:18 +0800 (11:32 -0400)  
"xlog" is not a particularly clear abbreviation for "write-ahead log",  
and it sometimes confuses users into believe that the contents of the  
"pg_xlog" directory are not critical data, leading to unpleasant  
consequences.  So, rename the directory to "pg_wal".  
This patch modifies pg_upgrade and pg_basebackup to understand both  
the old and new directory layouts; the former is necessary given the  
purpose of the tool, while the latter merely avoids an unnecessary  
backward-compatibility break.  
We may wish to consider renaming other programs, switches, and  
functions which still use the old "xlog" naming to also refer to  
"wal".  However, that's still under discussion, so let's do just this  
much for now.  
Michael Paquier  
Rename "pg_clog" directory to "pg_xact".  
author	Robert Haas <>	  
Fri, 17 Mar 2017 21:46:58 +0800 (09:46 -0400)  
committer	Robert Haas <>	  
Fri, 17 Mar 2017 21:48:38 +0800 (09:48 -0400)  
Names containing the letters "log" sometimes confuse users into  
believing that only non-critical data is present.  It is hoped  
this renaming will discourage ill-considered removals of transaction  
status data.  
Michael Paquier  
Change default of log_directory to 'log'  
author	Peter Eisentraut <>	  
Mon, 27 Mar 2017 22:34:33 +0800 (10:34 -0400)  
committer	Peter Eisentraut <>	  
Mon, 27 Mar 2017 22:34:33 +0800 (10:34 -0400)  
The previous default 'pg_log' might have indicated by its "pg_" prefix  
that it is an internal system directory.  The new default is more in  
line with the typical naming of directories with user-facing log files.  
Together with the renaming of pg_clog and pg_xlog, this should clear up  
that difference.  
Author: Andreas Karlsson <>  




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