Fix MERGE tuple count with DO NOTHING

Reporting tuples for which nothing is done is useless and goes against
the documented behavior, so don't do it.

Backpatch to 15.

Reported by: Luca Ferrari
Discussion: https://postgr.es/m/CAKoxK+42MmACUh6s8XzASQKizbzrtOGA6G1UjzCP75NcXHsiNw@mail.gmail.com

diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 0f357f822178cb0e965bfc2a338d60e9ca914590..b7ea953b55f09baf878f94570933d23710858b00 100644 (file)
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2799,7 +2799,7 @@ lmerge_matched:
                {
                        case TM_Ok:
                                /* all good; perform final actions */
-                               if (canSetTag)
+                               if (canSetTag && commandType != CMD_NOTHING)
                                        (estate->es_processed)++;
 
                                break;