Change data type of counters in BufferUsage and WalUsage from long to int64.

Previously long was used as the data type for some counters in BufferUsage
and WalUsage. But long is only four byte, e.g., on Windows, and it's entirely
possible to wrap a four byte counter. For example, emitting more than
four billion WAL records in one transaction isn't actually particularly rare.

To avoid the overflows of those counters, this commit changes the data type
of them from long to int64.

Suggested-by: Andres Freund
Author: Masahiro Ikeda
Reviewed-by: Fujii Masao
Discussion: https://postgr.es/m/20201221211650.k7b53tcnadrciqjo@alap3.anarazel.de
Discussion: https://postgr.es/m/af0964ac-7080-1984-dc23-513754987716@oss.nttdata.com

src/backend/access/heap/vacuumlazy.c

@@ -830,9 +830,9 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
 			}
 			appendStringInfo(&buf, _("system usage: %s\n"), pg_rusage_show(&ru0));
 			appendStringInfo(&buf,
-							 _("WAL usage: %ld records, %ld full page images, %llu bytes"),
-							 walusage.wal_records,
-							 walusage.wal_fpi,
+							 _("WAL usage: %lld records, %lld full page images, %llu bytes"),
+							 (long long) walusage.wal_records,
+							 (long long) walusage.wal_fpi,
 							 (unsigned long long) walusage.wal_bytes);
 
 			ereport(LOG,

src/backend/commands/explain.c

@@ -3526,17 +3526,17 @@ show_buffer_usage(ExplainState *es, const BufferUsage *usage, bool planning)
 			{
 				appendStringInfoString(es->str, " shared");
 				if (usage->shared_blks_hit > 0)
-					appendStringInfo(es->str, " hit=%ld",
-									 usage->shared_blks_hit);
+					appendStringInfo(es->str, " hit=%lld",
+									 (long long) usage->shared_blks_hit);
 				if (usage->shared_blks_read > 0)
-					appendStringInfo(es->str, " read=%ld",
-									 usage->shared_blks_read);
+					appendStringInfo(es->str, " read=%lld",
+									 (long long) usage->shared_blks_read);
 				if (usage->shared_blks_dirtied > 0)
-					appendStringInfo(es->str, " dirtied=%ld",
-									 usage->shared_blks_dirtied);
+					appendStringInfo(es->str, " dirtied=%lld",
+									 (long long) usage->shared_blks_dirtied);
 				if (usage->shared_blks_written > 0)
-					appendStringInfo(es->str, " written=%ld",
-									 usage->shared_blks_written);
+					appendStringInfo(es->str, " written=%lld",
+									 (long long) usage->shared_blks_written);
 				if (has_local || has_temp)
 					appendStringInfoChar(es->str, ',');
 			}
@@ -3544,17 +3544,17 @@ show_buffer_usage(ExplainState *es, const BufferUsage *usage, bool planning)
 			{
 				appendStringInfoString(es->str, " local");
 				if (usage->local_blks_hit > 0)
-					appendStringInfo(es->str, " hit=%ld",
-									 usage->local_blks_hit);
+					appendStringInfo(es->str, " hit=%lld",
+									 (long long) usage->local_blks_hit);
 				if (usage->local_blks_read > 0)
-					appendStringInfo(es->str, " read=%ld",
-									 usage->local_blks_read);
+					appendStringInfo(es->str, " read=%lld",
+									 (long long) usage->local_blks_read);
 				if (usage->local_blks_dirtied > 0)
-					appendStringInfo(es->str, " dirtied=%ld",
-									 usage->local_blks_dirtied);
+					appendStringInfo(es->str, " dirtied=%lld",
+									 (long long) usage->local_blks_dirtied);
 				if (usage->local_blks_written > 0)
-					appendStringInfo(es->str, " written=%ld",
-									 usage->local_blks_written);
+					appendStringInfo(es->str, " written=%lld",
+									 (long long) usage->local_blks_written);
 				if (has_temp)
 					appendStringInfoChar(es->str, ',');
 			}
@@ -3562,11 +3562,11 @@ show_buffer_usage(ExplainState *es, const BufferUsage *usage, bool planning)
 			{
 				appendStringInfoString(es->str, " temp");
 				if (usage->temp_blks_read > 0)
-					appendStringInfo(es->str, " read=%ld",
-									 usage->temp_blks_read);
+					appendStringInfo(es->str, " read=%lld",
+									 (long long) usage->temp_blks_read);
 				if (usage->temp_blks_written > 0)
-					appendStringInfo(es->str, " written=%ld",
-									 usage->temp_blks_written);
+					appendStringInfo(es->str, " written=%lld",
+									 (long long) usage->temp_blks_written);
 			}
 			appendStringInfoChar(es->str, '\n');
 		}
@@ -3638,11 +3638,11 @@ show_wal_usage(ExplainState *es, const WalUsage *usage)
 			appendStringInfoString(es->str, "WAL:");
 
 			if (usage->wal_records > 0)
-				appendStringInfo(es->str, " records=%ld",
-								 usage->wal_records);
+				appendStringInfo(es->str, " records=%lld",
+								 (long long) usage->wal_records);
 			if (usage->wal_fpi > 0)
-				appendStringInfo(es->str, " fpi=%ld",
-								 usage->wal_fpi);
+				appendStringInfo(es->str, " fpi=%lld",
+								 (long long) usage->wal_fpi);
 			if (usage->wal_bytes > 0)
 				appendStringInfo(es->str, " bytes=" UINT64_FORMAT,
 								 usage->wal_bytes);

src/include/executor/instrument.h

@@ -18,24 +18,24 @@
 
 typedef struct BufferUsage
 {
-	long		shared_blks_hit;	/* # of shared buffer hits */
-	long		shared_blks_read;	/* # of shared disk blocks read */
-	long		shared_blks_dirtied;	/* # of shared blocks dirtied */
-	long		shared_blks_written;	/* # of shared disk blocks written */
-	long		local_blks_hit; /* # of local buffer hits */
-	long		local_blks_read;	/* # of local disk blocks read */
-	long		local_blks_dirtied; /* # of local blocks dirtied */
-	long		local_blks_written; /* # of local disk blocks written */
-	long		temp_blks_read; /* # of temp blocks read */
-	long		temp_blks_written;	/* # of temp blocks written */
+	int64		shared_blks_hit;	/* # of shared buffer hits */
+	int64		shared_blks_read;	/* # of shared disk blocks read */
+	int64		shared_blks_dirtied;	/* # of shared blocks dirtied */
+	int64		shared_blks_written;	/* # of shared disk blocks written */
+	int64		local_blks_hit; /* # of local buffer hits */
+	int64		local_blks_read;	/* # of local disk blocks read */
+	int64		local_blks_dirtied; /* # of local blocks dirtied */
+	int64		local_blks_written; /* # of local disk blocks written */
+	int64		temp_blks_read; /* # of temp blocks read */
+	int64		temp_blks_written;	/* # of temp blocks written */
 	instr_time	blk_read_time;	/* time spent reading */
 	instr_time	blk_write_time; /* time spent writing */
 } BufferUsage;
 
 typedef struct WalUsage
 {
-	long		wal_records;	/* # of WAL records produced */
-	long		wal_fpi;		/* # of WAL full page images produced */
+	int64		wal_records;	/* # of WAL records produced */
+	int64		wal_fpi;		/* # of WAL full page images produced */
 	uint64		wal_bytes;		/* size of WAL records produced */
 } WalUsage;