+--test only index
+RESET plantuner.disable_index;
+RESET plantuner.enable_index;
+
+SET enable_seqscan=off;
+SET enable_bitmapscan=off;
+SET enable_indexonlyscan=off;
+
+SET plantuner.only_index="i1";
+SHOW plantuner.only_index;
+
+EXPLAIN (COSTS OFF) SELECT * FROM wow WHERE i = 0;
+
+SET plantuner.disable_index="i1,i2,i3";
+EXPLAIN (COSTS OFF) SELECT * FROM wow WHERE i = 0;
+
+SET plantuner.only_index="i2";
+EXPLAIN (COSTS OFF) SELECT * FROM wow WHERE i = 0;
+
+RESET plantuner.only_index;
+EXPLAIN (COSTS OFF) SELECT * FROM wow WHERE i = 0;