On 20.12.2012 12:08, Amit Kapila wrote:
On Wednesday, December 19, 2012 9:30 PM Heikki Linnakangas wrote:
In both checkpointer.c and bgwriter.c, we do this before entering the
main loop:
/*
* Use the recovery target timeline ID during recovery
*/
if (RecoveryInProgress())
ThisTimeLineID = GetRecoveryTargetTLI();
That seems reasonable. However, since it's only done once, when the
process starts up, ThisTimeLineID is never updated in those processes,
even though the startup process changes recovery target timeline.
That actually seems harmless to me, and I also haven't heard of any
complaints of misbehavior in 9.1 or 9.2 caused by that. I'm not sure
why
we bother to set ThisTimeLineID in those processes in the first place.
This is used in RemoveOldXlogFiles(), so if during recovery when it's not
set and
this function gets called, it might have some problem.
I think it could get called from CreateRestartPoint() during recovery.
Hmm, right, it's used for this:
XLogFileName(lastoff, ThisTimeLineID, segno);
The resulting lastoff string, which is a xlog filename like
"000000020000000000000008", is used to compare filenames of files in
pg_xlog. However, the tli part, first 8 characters, are ignored for
comparison purposes. In addition to that, 'lastoff' is printed in a
DEBUG2 line, purely for debugging purposes.
So I think we're good on that front. But I'll add a comment there, and
use 0 explicitly instead of ThisTimeLineID, for clarity.
- Heikki
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