|From:||Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>|
|To:||Andres Freund <andres(at)anarazel(dot)de>|
|Cc:||PostgreSQL Developers <pgsql-hackers(at)postgresql(dot)org>|
|Subject:||Re: checkpointer continuous flushing|
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Attached is very minor v5 update which does a rebase & completes the
cleanup of doing a full sort instead of a chuncked sort.
>> Attached is an updated version of the patch which turns the sort option
>> into a boolean, and also include the sort time in the checkpoint log.
>> There is still an open question about whether the sorting buffer allocation
>> is lost on some signals and should be reallocated in such event.
> In such case, probably the allocation should be managed from
> CheckpointerMain, and the lazy allocation could remain for other callers (I
> guess just "initdb").
> More open questions:
> - best name for the flush option (checkpoint_flush_to_disk,
> checkpoint_flush_on_write, checkpoint_flush, ...)
> - best name for the sort option (checkpoint_sort,
> checkpoint_sort_buffers, checkpoint_sort_ios, ...)
> Other nice-to-have inputs:
> - tests on a non-linux system with posix_fadvise
> (FreeBSD? others?)
> - tests on a large dedicated box
> Attached are some scripts to help with testing, if someone's feels like that:
> - cp_test.sh: run some tests, to adapt to one's setup...
> - cp_test_count.pl: show percent of late transactions
> - avg.py: show stats about stuff
> sh> grep 'progress: ' OUTPUT_FILE | cut -d' ' -f4 | avg.py
> *BEWARE* that if pgbench got stuck some "0" data are missing,
> look for the actual tps in the output file and for the line
> count to check whether it is the case... some currently submitted
> patch on pgbench helps, see https://commitfest.postgresql.org/5/199/
As this pgbench patch is now in master, pgbench is less likely to get
stuck, but check nevertheless that the number of progress line matches the
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