Hello.
Sometimes, I needed to infer where a past checkpoint make wal segments
unnecessary up to, or just to know the LSN at a past point in
time. But there's no convenient source for that.
The attached small patch enables me (or us) to do that by looking into
server log files.
> LOG: checkpoint complete: wrote 3 buffers (0.0%); 0 WAL file(s) added, 0
> removed, 0 recycled; write=0.008 s, sync=0.035 s, total=0.064 s; sync
> files=4, longest=0.017 s, average=0.009 s; distance=16420 kB, estimate=16420
> kB, redo=0/30091D8
Does that make sense?
regards.
--
Kyotaro Horiguchi
NTT Open Source Software Center
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index e51a7a749d..b6d7013a73 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -8761,7 +8761,7 @@ LogCheckpointEnd(bool restartpoint)
"%d WAL file(s) added, %d removed, %d recycled; "
"write=%ld.%03d s, sync=%ld.%03d s, total=%ld.%03d s; "
"sync files=%d, longest=%ld.%03d s, average=%ld.%03d s; "
- "distance=%d kB, estimate=%d kB",
+ "distance=%d kB, estimate=%d kB, redo=%X/%X",
CheckpointStats.ckpt_bufs_written,
(double) CheckpointStats.ckpt_bufs_written * 100 / NBuffers,
CheckpointStats.ckpt_segs_added,
@@ -8774,14 +8774,15 @@ LogCheckpointEnd(bool restartpoint)
longest_msecs / 1000, (int) (longest_msecs % 1000),
average_msecs / 1000, (int) (average_msecs % 1000),
(int) (PrevCheckPointDistance / 1024.0),
- (int) (CheckPointDistanceEstimate / 1024.0))));
+ (int) (CheckPointDistanceEstimate / 1024.0),
+ LSN_FORMAT_ARGS(ControlFile->checkPointCopy.redo))));
else
ereport(LOG,
(errmsg("checkpoint complete: wrote %d buffers (%.1f%%); "
"%d WAL file(s) added, %d removed, %d recycled; "
"write=%ld.%03d s, sync=%ld.%03d s, total=%ld.%03d s; "
"sync files=%d, longest=%ld.%03d s, average=%ld.%03d s; "
- "distance=%d kB, estimate=%d kB",
+ "distance=%d kB, estimate=%d kB, redo=%X/%X",
CheckpointStats.ckpt_bufs_written,
(double) CheckpointStats.ckpt_bufs_written * 100 / NBuffers,
CheckpointStats.ckpt_segs_added,
@@ -8794,7 +8795,8 @@ LogCheckpointEnd(bool restartpoint)
longest_msecs / 1000, (int) (longest_msecs % 1000),
average_msecs / 1000, (int) (average_msecs % 1000),
(int) (PrevCheckPointDistance / 1024.0),
- (int) (CheckPointDistanceEstimate / 1024.0))));
+ (int) (CheckPointDistanceEstimate / 1024.0),
+ LSN_FORMAT_ARGS(ControlFile->checkPointCopy.redo))));
}
/*
