Fix EXPLAIN MERGE output when no tuples are processed

An 'else' clause was misplaced in commit 598ac10be1c2, making zero-rows
output look a bit silly.  Add a test case for it.

Pointed out by Tom Lane.

Discussion: https://postgr.es/m/21030.1652893083@sss.pgh.pa.us

diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 2de546f16ebb368e2c2470827385bd3a773bd1dd..5d1f7089daf2238502c5afaf366891219f8ebef1 100644 (file)
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -4068,19 +4068,22 @@ show_modifytable_info(ModifyTableState *mtstate, List *ancestors,
            skipped_path = total - insert_path - update_path - delete_path;
            Assert(skipped_path >= 0);
 
-           if (es->format == EXPLAIN_FORMAT_TEXT && total > 0)
+           if (es->format == EXPLAIN_FORMAT_TEXT)
            {
-               ExplainIndentText(es);
-               appendStringInfoString(es->str, "Tuples:");
-               if (insert_path > 0)
-                   appendStringInfo(es->str, " inserted=%.0f", insert_path);
-               if (update_path > 0)
-                   appendStringInfo(es->str, " updated=%.0f", update_path);
-               if (delete_path > 0)
-                   appendStringInfo(es->str, " deleted=%.0f", delete_path);
-               if (skipped_path > 0)
-                   appendStringInfo(es->str, " skipped=%.0f", skipped_path);
-               appendStringInfoChar(es->str, '\n');
+               if (total > 0)
+               {
+                   ExplainIndentText(es);
+                   appendStringInfoString(es->str, "Tuples:");
+                   if (insert_path > 0)
+                       appendStringInfo(es->str, " inserted=%.0f", insert_path);
+                   if (update_path > 0)
+                       appendStringInfo(es->str, " updated=%.0f", update_path);
+                   if (delete_path > 0)
+                       appendStringInfo(es->str, " deleted=%.0f", delete_path);
+                   if (skipped_path > 0)
+                       appendStringInfo(es->str, " skipped=%.0f", skipped_path);
+                   appendStringInfoChar(es->str, '\n');
+               }
            }
            else
            {

diff --git a/src/test/regress/expected/merge.out b/src/test/regress/expected/merge.out
index 09d11ba742151d6323a175d73a4774d1ca28e0c1..af670e28e7f730478a18f20c93c9dca5c9a25cc3 100644 (file)
--- a/src/test/regress/expected/merge.out
+++ b/src/test/regress/expected/merge.out
@@ -1316,7 +1316,7 @@ BEGIN
         EXECUTE 'explain (analyze, timing off, summary off, costs off) ' ||
          query
     LOOP
-        ln := regexp_replace(ln, 'Memory: \S*',  'Memory: xxx');
+        ln := regexp_replace(ln, '(Memory( Usage)?|Buckets|Batches): \S*',  '\1: xxx', 'g');
         RETURN NEXT ln;
     END LOOP;
 END;
@@ -1432,6 +1432,24 @@ WHEN NOT MATCHED AND s.a < 20 THEN
                ->  Seq Scan on ex_mtarget t (actual rows=49 loops=1)
 (12 rows)
 
+-- nothing
+SELECT explain_merge('
+MERGE INTO ex_mtarget t USING ex_msource s ON t.a = s.a AND t.a < -1000
+WHEN MATCHED AND t.a < 10 THEN
+   DO NOTHING');
+                           explain_merge                            
+--------------------------------------------------------------------
+ Merge on ex_mtarget t (actual rows=0 loops=1)
+   ->  Hash Join (actual rows=0 loops=1)
+         Hash Cond: (s.a = t.a)
+         ->  Seq Scan on ex_msource s (actual rows=1 loops=1)
+         ->  Hash (actual rows=0 loops=1)
+               Buckets: xxx  Batches: xxx  Memory Usage: xxx
+               ->  Seq Scan on ex_mtarget t (actual rows=0 loops=1)
+                     Filter: (a < '-1000'::integer)
+                     Rows Removed by Filter: 54
+(9 rows)
+
 DROP TABLE ex_msource, ex_mtarget;
 DROP FUNCTION explain_merge(text);
 -- Subqueries

diff --git a/src/test/regress/sql/merge.sql b/src/test/regress/sql/merge.sql
index 8815e0cc4982b89c7af577e14c17b5553b2a9e4d..afeb212f3c826f9d67eaf531e7b29ff43aabd2a2 100644 (file)
--- a/src/test/regress/sql/merge.sql
+++ b/src/test/regress/sql/merge.sql
@@ -878,7 +878,7 @@ BEGIN
         EXECUTE 'explain (analyze, timing off, summary off, costs off) ' ||
          query
     LOOP
-        ln := regexp_replace(ln, 'Memory: \S*',  'Memory: xxx');
+        ln := regexp_replace(ln, '(Memory( Usage)?|Buckets|Batches): \S*',  '\1: xxx', 'g');
         RETURN NEXT ln;
     END LOOP;
 END;
@@ -920,6 +920,12 @@ WHEN MATCHED AND t.a >= 30 AND t.a <= 40 THEN
 WHEN NOT MATCHED AND s.a < 20 THEN
    INSERT VALUES (a, b)');
 
+-- nothing
+SELECT explain_merge('
+MERGE INTO ex_mtarget t USING ex_msource s ON t.a = s.a AND t.a < -1000
+WHEN MATCHED AND t.a < 10 THEN
+   DO NOTHING');
+
 DROP TABLE ex_msource, ex_mtarget;
 DROP FUNCTION explain_merge(text);