On Mon, Apr 06, 2020 at 02:34:36PM +0530, Amit Kapila wrote: > On Mon, Apr 6, 2020 at 1:53 PM Julien Rouhaud <rjuju...@gmail.com> wrote: > > > > On Mon, Apr 06, 2020 at 08:55:01AM +0530, Amit Kapila wrote: > > > > > > Here, we are not displaying Buffers related data, so why do we think > > > it is important to display WAL data? I see some point in displaying > > > Buffers and WAL data in a vacuum (verbose), but I feel it is better to > > > make a case for both the statistics together rather than just > > > displaying one and leaving other. I think the other change related to > > > autovacuum stats seems okay to me. > > > > One thing is that the amount of WAL, and more precisely FPW, is quite > > unpredictable wrt. vacuum and even more anti-wraparound vacuum, so this is > > IMHO > > a very useful metric. > > > > I agree but we already have a way via pg_stat_statements to find it if > the metric is so useful. >
Agreed. > > > That being said I totally agree with you that both > > should be displayed. Should I send a patch to also expose it? > > > > I think this should be a separate proposal. Let's not add things > unless they are really essential. We can separately discuss of > enhancing vacuum verbose for Buffer and WAL usage stats and see if > others also find that information useful. I think you can send a > patch by removing the code I mentioned above if you agree. Thanks for > working on this. Thanks! v15 attached.
>From 9f4cbb1817372628a3fc7b3fffe82ec2a3942f91 Mon Sep 17 00:00:00 2001 From: Julien Rouhaud <julien.rouh...@free.fr> Date: Thu, 19 Mar 2020 16:08:47 +0100 Subject: [PATCH v15] Expose WAL usage counters in verbose (auto)vacuum output. Author: Julien Rouhaud Reviewed-by: Fuji Masao, Amit Kapila, Dilip Kumar Discussion: https://postgr.es/m/CAB-hujrP8ZfUkvL5OYETipQwA=e3n7oqHFU=4zlxws_cza3...@mail.gmail.com --- src/backend/access/heap/vacuumlazy.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c index 3ca7f5d136..877512fae4 100644 --- a/src/backend/access/heap/vacuumlazy.c +++ b/src/backend/access/heap/vacuumlazy.c @@ -410,6 +410,8 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params, int nindexes; PGRUsage ru0; TimestampTz starttime = 0; + WalUsage walusage_start = pgWalUsage; + WalUsage walusage = {0, 0, 0}; long secs; int usecs; double read_rate, @@ -614,6 +616,9 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params, TimestampDifference(starttime, endtime, &secs, &usecs); + memset(&walusage, 0, sizeof(WalUsage)); + WalUsageAccumDiff(&walusage, &pgWalUsage, &walusage_start); + read_rate = 0; write_rate = 0; if ((secs > 0) || (usecs > 0)) @@ -666,7 +671,13 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params, (long long) VacuumPageDirty); appendStringInfo(&buf, _("avg read rate: %.3f MB/s, avg write rate: %.3f MB/s\n"), read_rate, write_rate); - appendStringInfo(&buf, _("system usage: %s"), pg_rusage_show(&ru0)); + appendStringInfo(&buf, _("system usage: %s\n"), pg_rusage_show(&ru0)); + appendStringInfo(&buf, + _("WAL usage: %ld records, %ld full page writes, " + UINT64_FORMAT " bytes"), + walusage.wal_records, + walusage.wal_num_fpw, + walusage.wal_bytes); ereport(LOG, (errmsg_internal("%s", buf.data))); @@ -1727,6 +1738,7 @@ lazy_scan_heap(Relation onerel, VacuumParams *params, LVRelStats *vacrelstats, "%u pages are entirely empty.\n", empty_pages), empty_pages); + appendStringInfo(&buf, _("%s."), pg_rusage_show(&ru0)); ereport(elevel, -- 2.20.1
