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Have VACUUM log number of skipped pages due to pins 

Author: Jim Nasby, some kibitzing by Heikki Linnankangas.
Discussion leading to current behavior and precise wording fueled by
thoughts from Robert Haas and Andres Freund.
This commit is contained in:
Alvaro Herrera 2014-12-18 17:18:33 -03:00
parent 4a14f13a0a
commit 35192f0626
2 changed files with 72 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
doc/src/sgml/ref/vacuum.sgml
View File

@ -252,6 +252,7 @@ DETAIL: CPU 0.01s/0.06u sec elapsed 0.07 sec.
INFO: "onek": found 3000 removable, 1000 nonremovable tuples in 143 pages
DETAIL: 0 dead tuples cannot be removed yet.
There were 0 unused item pointers.
Skipped 0 pages due to buffer pins.
0 pages are entirely empty.
CPU 0.07s/0.39u sec elapsed 1.56 sec.
INFO: analyzing "public.onek"

99
src/backend/commands/vacuumlazy.c
View File

@ -105,6 +105,7 @@ typedef struct LVRelStats
BlockNumber old_rel_pages; /* previous value of pg_class.relpages */
BlockNumber rel_pages; /* total number of pages */
BlockNumber scanned_pages; /* number of pages we examined */
BlockNumber pinned_pages; /* # of pages we could not initially lock */
double scanned_tuples; /* counts only tuples on scanned pages */
double old_rel_tuples; /* previous value of pg_class.reltuples */
double new_rel_tuples; /* new estimated total # of tuples */
@ -332,6 +333,7 @@ lazy_vacuum_rel(Relation onerel, VacuumStmt *vacstmt,
TimestampDifferenceExceeds(starttime, endtime,
Log_autovacuum_min_duration))
{
StringInfoData buf;
TimestampDifference(starttime, endtime, &secs, &usecs);
read_rate = 0;
@ -343,27 +345,47 @@ lazy_vacuum_rel(Relation onerel, VacuumStmt *vacstmt,
write_rate = (double) BLCKSZ *VacuumPageDirty / (1024 * 1024) /
(secs + usecs / 1000000.0);
}
/*
* This is pretty messy, but we split it up so that we can skip
* emitting individual parts of the message when not applicable.
*/
initStringInfo(&buf);
appendStringInfo(&buf, _("automatic vacuum of table \"%s.%s.%s\": index scans: %d\n"),
get_database_name(MyDatabaseId),
get_namespace_name(RelationGetNamespace(onerel)),
RelationGetRelationName(onerel),
vacrelstats->num_index_scans);
appendStringInfo(&buf, _("pages: %d removed, %d remain\n"),
vacrelstats->pages_removed,
vacrelstats->rel_pages);
if (vacrelstats->pinned_pages > 0)
{
if (scan_all)
appendStringInfo(&buf, _("waited for %d buffer pins\n"),
vacrelstats->pinned_pages);
else
appendStringInfo(&buf,
_("skipped %d pages due to buffer pins\n"),
vacrelstats->pinned_pages);
}
appendStringInfo(&buf,
_("tuples: %.0f removed, %.0f remain, %.0f are dead but not yet removable\n"),
vacrelstats->tuples_deleted,
vacrelstats->new_rel_tuples,
vacrelstats->new_dead_tuples);
appendStringInfo(&buf,
_("buffer usage: %d hits, %d misses, %d dirtied\n"),
VacuumPageHit,
VacuumPageMiss,
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));
ereport(LOG,
(errmsg("automatic vacuum of table \"%s.%s.%s\": index scans: %d\n"
"pages: %d removed, %d remain\n"
"tuples: %.0f removed, %.0f remain, %.0f are dead but not yet removable\n"
"buffer usage: %d hits, %d misses, %d dirtied\n"
"avg read rate: %.3f MB/s, avg write rate: %.3f MB/s\n"
"system usage: %s",
get_database_name(MyDatabaseId),
get_namespace_name(RelationGetNamespace(onerel)),
RelationGetRelationName(onerel),
vacrelstats->num_index_scans,
vacrelstats->pages_removed,
vacrelstats->rel_pages,
vacrelstats->tuples_deleted,
vacrelstats->new_rel_tuples,
vacrelstats->new_dead_tuples,
VacuumPageHit,
VacuumPageMiss,
VacuumPageDirty,
read_rate, write_rate,
pg_rusage_show(&ru0))));
(errmsg_internal("%s", buf.data)));
pfree(buf.data);
}
}
}
@ -438,6 +460,7 @@ lazy_scan_heap(Relation onerel, LVRelStats *vacrelstats,
BlockNumber next_not_all_visible_block;
bool skipping_all_visible_blocks;
xl_heap_freeze_tuple *frozen;
StringInfoData buf;
pg_rusage_init(&ru0);
@ -611,6 +634,8 @@ lazy_scan_heap(Relation onerel, LVRelStats *vacrelstats,
/* We need buffer cleanup lock so that we can prune HOT chains. */
if (!ConditionalLockBufferForCleanup(buf))
{
vacrelstats->pinned_pages++;
/*
* If we're not scanning the whole relation to guard against XID
* wraparound, it's OK to skip vacuuming a page. The next vacuum
@ -1094,19 +1119,37 @@ lazy_scan_heap(Relation onerel, LVRelStats *vacrelstats,
RelationGetRelationName(onerel),
tups_vacuumed, vacuumed_pages)));
/*
* This is pretty messy, but we split it up so that we can skip emitting
* individual parts of the message when not applicable.
*/
initStringInfo(&buf);
appendStringInfo(&buf,
_("%.0f dead row versions cannot be removed yet.\n"),
nkeep);
appendStringInfo(&buf, _("There were %.0f unused item pointers.\n"),
nunused);
if (vacrelstats->pinned_pages > 0)
{
if (scan_all)
appendStringInfo(&buf, _("Waited for %d buffer pins.\n"),
vacrelstats->pinned_pages);
else
appendStringInfo(&buf, _("Skipped %u pages due to buffer pins.\n"),
vacrelstats->pinned_pages);
}
appendStringInfo(&buf, _("%u pages are entirely empty.\n"),
empty_pages);
appendStringInfo(&buf, _("%s."),
pg_rusage_show(&ru0));
ereport(elevel,
(errmsg("\"%s\": found %.0f removable, %.0f nonremovable row versions in %u out of %u pages",
RelationGetRelationName(onerel),
tups_vacuumed, num_tuples,
vacrelstats->scanned_pages, nblocks),
errdetail("%.0f dead row versions cannot be removed yet.\n"
"There were %.0f unused item pointers.\n"
"%u pages are entirely empty.\n"
"%s.",
nkeep,
nunused,
empty_pages,
pg_rusage_show(&ru0))));
errdetail_internal("%s", buf.data)));
pfree(buf.data);
}