Horton

Re: shared-memory based stats collector - v66

Melanie Plageman <melanieplageman@gmail.com>

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From: Melanie Plageman <melanieplageman@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: Kyotaro Horiguchi <horikyota.ntt@gmail.com>, Ibrar Ahmed <ibrar.ahmad@gmail.com>, masao.fujii@oss.nttdata.com, gkokolatos@protonmail.com, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-03-20T20:56:37Z
Lists: pgsql-hackers

Attachments

On Sun, Mar 20, 2022 at 12:58 PM Andres Freund <andres@anarazel.de> wrote:
>
> Hi,
>
> On 2022-03-20 12:32:39 -0400, Melanie Plageman wrote:
> > Attached is a TAP test to check that stats are cleaned up on a physical
> > replica after the objects they concern are dropped on the primary.
>
> Thanks!
>
>
> > I'm not sure that the extra force next flush on standby is needed after
> > drop on primary since drop should report stats and I wait for catchup.
>
> A drop doesn't force stats in other sessions to be flushed immediately, so
> unless I misunderstand, yes, it's needed.
>
>
> > Also, I don't think the tests with DROP SCHEMA actually exercise another
> > code path, so it might be worth cutting those.
>
> > +/*
> > + * Checks for presence of stats for object with provided object oid of kind
> > + * specified in the type string in database of provided database oid.
> > + *
> > + * For subscription stats, only the objoid will be used. For database stats,
> > + * only the dboid will be used. The value passed in for the unused parameter is
> > + * discarded.
> > + * TODO: should it be 'pg_stat_stats_present' instead of 'pg_stat_stats_exist'?
> > + */
> > +Datum
> > +pg_stat_stats_exist(PG_FUNCTION_ARGS)
>
> Should we revoke stats for this one from PUBLIC (similar to the reset functions)?
>
>
> > +# Set track_functions to all on standby
> > +$node_standby->append_conf('postgresql.conf', "track_functions = 'all'");
>
> That should already be set, cloning from the primary includes the
> configuration from that point in time.
>
> > +$node_standby->restart;
>
> FWIW, it'd also only require a reload....
>

Addressed all of these points in
v2-0001-add-replica-cleanup-tests.patch

also added a new test file in
v2-0002-Add-TAP-test-for-discarding-stats-after-crash.patch
testing correct behavior after a crash and when stats file is invalid

- Melanie

Commits

  1. Improve comment about dropped entries in pgstat.c

  2. Fix temporary memory leak in system table index scans

  3. pgstat: set timestamps of fixed-numbered stats after a crash.

  4. pgstat: Update docs to match the shared memory stats reality.

  5. pgstat: Hide instability in stats.spec with -DCATCACHE_FORCE_RELEASE.

  6. pgstat: add/extend tests for resetting various kinds of stats.

  7. Add minimal tests for recovery conflict handling.

  8. pgstat: test stats interactions with physical replication.

  9. pgstat: add tests for handling of restarts, including crashes.

  10. pgstat: add tests for transaction behaviour, 2PC, function stats.

  11. pgstat: add pg_stat_have_stats() test helper.

  12. pgstat: add pg_stat_force_next_flush(), use it to simplify tests.

  13. pgstat: move pgstat.c to utils/activity.

  14. pgstat: store statistics in shared memory.

  15. pgstat: remove stats_temp_directory.

  16. pgstat: rename STATS_COLLECTOR GUC group to STATS_CUMULATIVE.

  17. pgstat: revise replication slot API in preparation for shared memory stats.

  18. pgstat: scaffolding for transactional stats creation / drop.

  19. pgstat: introduce PgStat_Kind enum.

  20. pgstat: prepare APIs used by pgstatfuncs for shared memory stats.

  21. pgstat: add pgstat_copy_relation_stats().

  22. pgstat: rename some pgstat_send_* functions to pgstat_report_*.

  23. pgstat: stats collector references in comments.

  24. pgstat: move transactional code into pgstat_xact.c.

  25. dsm: allow use in single user mode.

  26. dshash: revise sequential scan support.

  27. pgstat: remove some superflous comments from pgstat.h.

  28. pgstat: reorder pgstat.[ch] contents.

  29. pgstat: split different types of stats into separate files.

  30. pgstat: introduce pgstat_relation_should_count().

  31. pgstat: separate "xact level" handling out of relation specific functions.

  32. pgstat: rename pgstat_initstats() to pgstat_relation_init().

  33. pgstat: split out WAL handling from pgstat_{initialize,report_stat}.

  34. pgstat: run pgindent on pgstat.c/h.

  35. pgstat: split relation, database handling out of pgstat_report_stat().

  36. Move code around in StartupXLOG().

  37. pgstat: Prepare to use mechanism for truncated rels also for droppped rels.

  38. pgstat: Split out relation stats handling from AtEO[Sub]Xact_PgStat() etc.

  39. pgstat: Schedule per-backend pgstat shutdown via before_shmem_exit().

  40. Schedule ShutdownXLOG() in single user mode using before_shmem_exit().

  41. Make parallel worker shutdown complete entirely via before_shmem_exit().

  42. pgstat: Bring up pgstat in BaseInit() to fix uninitialized use of pgstat by AV.

  43. pgstat: split reporting/fetching of bgwriter and checkpointer stats.

  44. Split backend status and progress related functionality out of pgstat.c.

  45. Split wait event related code from pgstat.[ch] into wait_event.[ch].

  46. Make archiver process an auxiliary process.

  47. Force to send remaining WAL stats to the stats collector at walwriter exit.

  48. Add pg_stat_database counters for sessions and session time

  49. Collect statistics about SLRU caches

  50. Don't run atexit callbacks in quickdie signal handlers.

  51. Create a "fast path" for acquiring weak relation locks.