Prevent bitmap heap scans from showing unnecessary block info in EXPLAIN ANALYZE.

MasaoFujii · MasaoFujii · commit d4635b16fe3d · 2014-07-14T20:40:14.000+09:00
EXPLAIN ANALYZE shows the information of the numbers of exact/lossy blocks which
bitmap heap scan processes. But, previously, when those numbers were both zero,
it displayed only the prefix "Heap Blocks:" in TEXT output format. This is strange
and would confuse the users. So this commit suppresses such unnecessary information.

Backpatch to 9.4 where EXPLAIN ANALYZE was changed so that such information was
displayed.

Etsuro Fujita
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
@@ -1937,13 +1937,16 @@ show_tidbitmap_info(BitmapHeapScanState *planstate, ExplainState *es)
 	}
 	else
 	{
-		appendStringInfoSpaces(es->str, es->indent * 2);
-		appendStringInfoString(es->str, "Heap Blocks:");
-		if (planstate->exact_pages > 0)
-			appendStringInfo(es->str, " exact=%ld", planstate->exact_pages);
-		if (planstate->lossy_pages > 0)
-			appendStringInfo(es->str, " lossy=%ld", planstate->lossy_pages);
-		appendStringInfoChar(es->str, '\n');
+		if (planstate->exact_pages > 0 || planstate->lossy_pages > 0)
+		{
+			appendStringInfoSpaces(es->str, es->indent * 2);
+			appendStringInfoString(es->str, "Heap Blocks:");
+			if (planstate->exact_pages > 0)
+				appendStringInfo(es->str, " exact=%ld", planstate->exact_pages);
+			if (planstate->lossy_pages > 0)
+				appendStringInfo(es->str, " lossy=%ld", planstate->lossy_pages);
+			appendStringInfoChar(es->str, '\n');
+		}
 	}
 }
 

Original file line number	Diff line number	Diff line change
`@@ -1937,13 +1937,16 @@ show_tidbitmap_info(BitmapHeapScanState planstate, ExplainState es)`
`1937`	`1937`	`}`
`1938`	`1938`	`else`
`1939`	`1939`	`{`
`1940`		`- appendStringInfoSpaces(es->str, es->indent * 2);`
`1941`		`- appendStringInfoString(es->str, "Heap Blocks:");`
`1942`		`- if (planstate->exact_pages > 0)`
`1943`		`- appendStringInfo(es->str, " exact=%ld", planstate->exact_pages);`
`1944`		`- if (planstate->lossy_pages > 0)`
`1945`		`- appendStringInfo(es->str, " lossy=%ld", planstate->lossy_pages);`
`1946`		`- appendStringInfoChar(es->str, '\n');`
	`1940`	`+ if (planstate->exact_pages > 0 \|\| planstate->lossy_pages > 0)`
	`1941`	`+ {`
	`1942`	`+ appendStringInfoSpaces(es->str, es->indent * 2);`
	`1943`	`+ appendStringInfoString(es->str, "Heap Blocks:");`
	`1944`	`+ if (planstate->exact_pages > 0)`
	`1945`	`+ appendStringInfo(es->str, " exact=%ld", planstate->exact_pages);`
	`1946`	`+ if (planstate->lossy_pages > 0)`
	`1947`	`+ appendStringInfo(es->str, " lossy=%ld", planstate->lossy_pages);`
	`1948`	`+ appendStringInfoChar(es->str, '\n');`
	`1949`	`+ }`
`1947`	`1950`	`}`
`1948`	`1951`	`}`
`1949`	`1952`