From 3881aedbcfb5e1e36e2860d081e045fb5283f8cc Mon Sep 17 00:00:00 2001 From: Heikki Linnakangas <heikki.linnakangas@iki.fi> Date: Thu, 20 Dec 2012 21:30:59 +0200 Subject: [PATCH] Fix recycling of WAL segments after changing recovery target timeline. After the recovery target timeline is changed, we would still recycle and preallocate WAL segments on the old target timeline. Those WAL segments created for the old timeline are a waste of space, although otherwise harmless. The problem is that when installing a recycled WAL segment as a future one, ThisTimeLineID is used to construct the filename. ThisTimeLineID is initialized in the checkpointer process to the recovery target timeline at startup, but it was not updated when the startup process chooses a new target timeline (recovery_target_timeline='latest'). To fix, always update ThisTimeLineID before recycling WAL segments at a restartpoint. This still leaves a small window where we might install WAL segments under wrong timeline ID, if the target timeline is changed just as we're about to start recycling. Also, when we're not on the target timeline yet, but still replaying some older timeline, we'll install WAL segments to the newer timeline anyway and they will still go wasted. We'll just live with the waste in that situation. Commit to 9.2 and 9.1. Older versions didn't change recovery target timeline after startup, and for master, I'll commit a slightly different variant of this. --- src/backend/access/transam/xlog.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 1d1e47b588c..5df6063be99 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -8415,6 +8415,13 @@ CreateRestartPoint(int flags) KeepLogSeg(endptr, &_logId, &_logSeg); PrevLogSeg(_logId, _logSeg); + + /* + * Update ThisTimeLineID to the recovery target timeline, so that + * we install any recycled segments on the correct timeline. + */ + ThisTimeLineID = GetRecoveryTargetTLI(); + RemoveOldXlogFiles(_logId, _logSeg, endptr); /* -- GitLab