From 35192f0626ccc1729eb6220a5fa04699fd62e04e Mon Sep 17 00:00:00 2001
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: Thu, 18 Dec 2014 17:18:33 -0300
Subject: [PATCH] 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.
---
doc/src/sgml/ref/vacuum.sgml | 1 +
src/backend/commands/vacuumlazy.c | 99 ++++++++++++++++++++++---------
2 files changed, 72 insertions(+), 28 deletions(-)
diff --git a/doc/src/sgml/ref/vacuum.sgml b/doc/src/sgml/ref/vacuum.sgml
index 450c94fcd3e..19fd748dde0 100644
--- a/doc/src/sgml/ref/vacuum.sgml
+++ b/doc/src/sgml/ref/vacuum.sgml
@@ -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"
diff --git a/src/backend/commands/vacuumlazy.c b/src/backend/commands/vacuumlazy.c
index 6db6c5cf472..3e68f951e29 100644
--- a/src/backend/commands/vacuumlazy.c
+++ b/src/backend/commands/vacuumlazy.c
@@ -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);
}
--
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