Make EXPLAIN (BUFFERS) track blocks dirtied, as well as those written.

Also expose the new counters through pg_stat_statements.

Patch by me.  Review by Fujii Masao and Greg Smith.

5 files changed, 22 insertions, 3 deletions

diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index a1692f82ae8..93b1f34ca0c 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -1183,12 +1183,14 @@ ExplainNode(PlanState *planstate, List *ancestors,
 		{
 			bool		has_shared = (usage->shared_blks_hit > 0 ||
 									  usage->shared_blks_read > 0 ||
-									  usage->shared_blks_written);
+									  usage->shared_blks_dirtied > 0 ||
+									  usage->shared_blks_written > 0);
 			bool		has_local = (usage->local_blks_hit > 0 ||
 									 usage->local_blks_read > 0 ||
-									 usage->local_blks_written);
+									 usage->local_blks_dirtied > 0 ||
+									 usage->local_blks_written > 0);
 			bool		has_temp = (usage->temp_blks_read > 0 ||
-									usage->temp_blks_written);
+									usage->temp_blks_written > 0);
 
 			/* Show only positive counter values. */
 			if (has_shared || has_local || has_temp)
@@ -1205,6 +1207,9 @@ ExplainNode(PlanState *planstate, List *ancestors,
 					if (usage->shared_blks_read > 0)
 						appendStringInfo(es->str, " read=%ld",
 										 usage->shared_blks_read);
+					if (usage->shared_blks_dirtied > 0)
+						appendStringInfo(es->str, " dirtied=%ld",
+										 usage->shared_blks_dirtied);
 					if (usage->shared_blks_written > 0)
 						appendStringInfo(es->str, " written=%ld",
 										 usage->shared_blks_written);
@@ -1220,6 +1225,9 @@ ExplainNode(PlanState *planstate, List *ancestors,
 					if (usage->local_blks_read > 0)
 						appendStringInfo(es->str, " read=%ld",
 										 usage->local_blks_read);
+					if (usage->local_blks_dirtied > 0)
+						appendStringInfo(es->str, " dirtied=%ld",
+										 usage->local_blks_dirtied);
 					if (usage->local_blks_written > 0)
 						appendStringInfo(es->str, " written=%ld",
 										 usage->local_blks_written);
@@ -1243,9 +1251,11 @@ ExplainNode(PlanState *planstate, List *ancestors,
 		{
 			ExplainPropertyLong("Shared Hit Blocks", usage->shared_blks_hit, es);
 			ExplainPropertyLong("Shared Read Blocks", usage->shared_blks_read, es);
+			ExplainPropertyLong("Shared Dirtied Blocks", usage->shared_blks_dirtied, es);
 			ExplainPropertyLong("Shared Written Blocks", usage->shared_blks_written, es);
 			ExplainPropertyLong("Local Hit Blocks", usage->local_blks_hit, es);
 			ExplainPropertyLong("Local Read Blocks", usage->local_blks_read, es);
+			ExplainPropertyLong("Local Dirtied Blocks", usage->local_blks_dirtied, es);
 			ExplainPropertyLong("Local Written Blocks", usage->local_blks_written, es);
 			ExplainPropertyLong("Temp Read Blocks", usage->temp_blks_read, es);
 			ExplainPropertyLong("Temp Written Blocks", usage->temp_blks_written, es);
diff --git a/src/backend/executor/instrument.c b/src/backend/executor/instrument.c
index 2c749b13cd8..6e9f450d688 100644
--- a/src/backend/executor/instrument.c
+++ b/src/backend/executor/instrument.c
@@ -137,9 +137,11 @@ BufferUsageAccumDiff(BufferUsage *dst,
 {
 	dst->shared_blks_hit += add->shared_blks_hit - sub->shared_blks_hit;
 	dst->shared_blks_read += add->shared_blks_read - sub->shared_blks_read;
+	dst->shared_blks_dirtied += add->shared_blks_dirtied - sub->shared_blks_dirtied;
 	dst->shared_blks_written += add->shared_blks_written - sub->shared_blks_written;
 	dst->local_blks_hit += add->local_blks_hit - sub->local_blks_hit;
 	dst->local_blks_read += add->local_blks_read - sub->local_blks_read;
+	dst->local_blks_dirtied += add->local_blks_dirtied - sub->local_blks_dirtied;
 	dst->local_blks_written += add->local_blks_written - sub->local_blks_written;
 	dst->temp_blks_read += add->temp_blks_read - sub->temp_blks_read;
 	dst->temp_blks_written += add->temp_blks_written - sub->temp_blks_written;
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 1adb6d360dd..3924a51c0c6 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -988,6 +988,7 @@ MarkBufferDirty(Buffer buffer)
 	if (dirtied)
 	{
 		VacuumPageDirty++;
+		pgBufferUsage.shared_blks_dirtied++;
 		if (VacuumCostActive)
 			VacuumCostBalance += VacuumCostPageDirty;
 		if (ProcGlobal->bgwriterLatch)
diff --git a/src/backend/storage/buffer/localbuf.c b/src/backend/storage/buffer/localbuf.c
index 096d36a233b..63c14f7300c 100644
--- a/src/backend/storage/buffer/localbuf.c
+++ b/src/backend/storage/buffer/localbuf.c
@@ -276,6 +276,10 @@ MarkLocalBufferDirty(Buffer buffer)
 	Assert(LocalRefCount[bufid] > 0);
 
 	bufHdr = &LocalBufferDescriptors[bufid];
+
+	if (!(bufHdr->flags & BM_DIRTY))
+		pgBufferUsage.local_blks_dirtied++;
+
 	bufHdr->flags |= BM_DIRTY;
 }
 
diff --git a/src/include/executor/instrument.h b/src/include/executor/instrument.h
index 084302e4e7e..066f684f330 100644
--- a/src/include/executor/instrument.h
+++ b/src/include/executor/instrument.h
@@ -20,9 +20,11 @@ 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 shared 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 */