diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index ab6a889b12..2ff23abbe9 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -657,10 +657,10 @@ refresh_by_match_merge(Oid matviewOid, Oid tempOid, Oid relowner,
 	appendStringInfo(&querybuf,
 					 "SELECT newdata FROM %s newdata "
 					 "WHERE newdata IS NOT NULL AND EXISTS "
-					 "(SELECT * FROM %s newdata2 WHERE newdata2 IS NOT NULL "
+					 "(SELECT 1 FROM %s newdata2 WHERE newdata2 IS NOT NULL "
 					 "AND newdata2 OPERATOR(pg_catalog.*=) newdata "
 					 "AND newdata2.ctid OPERATOR(pg_catalog.<>) "
-					 "newdata.ctid) LIMIT 1",
+					 "newdata.ctid)",
 					 tempname, tempname);
 	if (SPI_execute(querybuf.data, false, 1) != SPI_OK_SELECT)
 		elog(ERROR, "SPI_exec failed: %s", querybuf.data);