We recently noticed that vacuum buffer counters wraparound in extreme
cases, with ridiculous results. Example:
2020-01-06 16:38:38.010 EST [45625-1] app= LOG: automatic vacuum of table
"somtab.sf.foobar": index scans: 17
pages: 0 removed, 207650641 remain, 0 skipped due to pins, 13419403
skipped frozen
tuples: 141265419 removed, 3186614627 remain, 87783760 are dead but not
yet removable
buffer usage: -2022059267 hits, -17141881 misses, 1252507767 dirtied
avg read rate: -0.043 MB/s, avg write rate: 3.146 MB/s
system usage: CPU 107819.92s/2932957.75u sec elapsed 3110498.10 sec
That's to be expected, as tables exist that are large enough for 4 billion
buffer accesses to be a possibility. Let's widen the counters, as in the
attached patch.
I propose to backpatch this.
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 8ce501151e..049ec2703b 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -614,7 +614,7 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params,
vacrelstats->new_dead_tuples,
OldestXmin);
appendStringInfo(&buf,
- _("buffer usage: %d hits, %d misses, %d dirtied\n"),
+ _("buffer usage: %zd hits, %zd misses, %zd dirtied\n"),
VacuumPageHit,
VacuumPageMiss,
VacuumPageDirty);
diff --git a/src/backend/utils/init/globals.c b/src/backend/utils/init/globals.c
index b1f6291b99..eb19644419 100644
--- a/src/backend/utils/init/globals.c
+++ b/src/backend/utils/init/globals.c
@@ -140,9 +140,9 @@ int VacuumCostPageDirty = 20;
int VacuumCostLimit = 200;
double VacuumCostDelay = 0;
-int VacuumPageHit = 0;
-int VacuumPageMiss = 0;
-int VacuumPageDirty = 0;
+int64 VacuumPageHit = 0;
+int64 VacuumPageMiss = 0;
+int64 VacuumPageDirty = 0;
int VacuumCostBalance = 0; /* working state for vacuum */
bool VacuumCostActive = false;
diff --git a/src/include/miscadmin.h b/src/include/miscadmin.h
index 62d64aa0a1..f985453ec3 100644
--- a/src/include/miscadmin.h
+++ b/src/include/miscadmin.h
@@ -252,9 +252,9 @@ extern int VacuumCostPageDirty;
extern int VacuumCostLimit;
extern double VacuumCostDelay;
-extern int VacuumPageHit;
-extern int VacuumPageMiss;
-extern int VacuumPageDirty;
+extern int64 VacuumPageHit;
+extern int64 VacuumPageMiss;
+extern int64 VacuumPageDirty;
extern int VacuumCostBalance;
extern bool VacuumCostActive;
