pgstat: Hide instability in stats.spec with -DCATCACHE_FORCE_RELEASE.

With -DCATCACHE_FORCE_RELEASE a few tests failed. Those were trying to test
behavior in the absence of invalidation processing and
-DCATCACHE_FORCE_RELEASE obviously adds a lot of invalidation processing. The
test already tried to handle debug_discard_caches > 0, by disabling it for
individual tests.

Instead hide potentially problematic function calls in a wrapper function that
catches the does-not-exist error. The error isn't the actually interesting
bit, it's whether the stats entry still exist afterwards.

I confirmed that the tests still catches leaked function stats if I nuke the
protections against that in pgstat_function.c.

Per buildfarm animal prion.

Discussion: https://postgr.es/m/[email protected]

3 files changed, 172 insertions, 170 deletions

diff --git a/src/test/isolation/expected/stats.out b/src/test/isolation/expected/stats.out
index 12234fbcd9..8bf6e57d0b 100644
--- a/src/test/isolation/expected/stats.out
+++ b/src/test/isolation/expected/stats.out
@@ -33,7 +33,7 @@ test_stat_func
               
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -87,7 +87,7 @@ test_stat_func
               
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -174,7 +174,7 @@ test_stat_func
               
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -257,7 +257,7 @@ test_stat_func
               
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -360,7 +360,7 @@ test_stat_func
 (1 row)
 
 step s1_commit: COMMIT;
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -472,7 +472,7 @@ test_stat_func|                         2|t               |t
 (1 row)
 
 step s1_commit: COMMIT;
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -584,7 +584,7 @@ test_stat_func|                         2|t               |t
 (1 row)
 
 step s1_rollback: ROLLBACK;
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -619,7 +619,7 @@ test_stat_func|                         3|t               |t
 (1 row)
 
 
-starting permutation: s1_track_funcs_all s2_track_funcs_all s2_func_call s2_ff s2_begin s2_func_call s1_func_drop s1_func_stats s2_commit s2_ff s1_func_stats s2_func_stats
+starting permutation: s1_track_funcs_all s2_track_funcs_all s2_func_call s2_ff s2_begin s2_func_call_ifexists s1_func_drop s1_func_stats s2_commit s2_ff s1_func_stats s2_func_stats
 pg_stat_force_next_flush
 ------------------------
                         
@@ -640,10 +640,10 @@ pg_stat_force_next_flush
 (1 row)
 
 step s2_begin: BEGIN;
-step s2_func_call: SELECT test_stat_func()
-test_stat_func
---------------
-              
+step s2_func_call_ifexists: SELECT test_stat_func_ifexists();
+test_stat_func_ifexists
+-----------------------
+                       
 (1 row)
 
 step s1_func_drop: DROP FUNCTION test_stat_func();
@@ -697,7 +697,7 @@ test_stat_func|                          |                |
 (1 row)
 
 
-starting permutation: s1_track_funcs_all s2_track_funcs_all s2_begin s2_func_call s1_func_drop s1_func_stats s2_commit s2_ff s1_func_stats s2_func_stats
+starting permutation: s1_track_funcs_all s2_track_funcs_all s2_begin s2_func_call_ifexists s1_func_drop s1_func_stats s2_commit s2_ff s1_func_stats s2_func_stats
 pg_stat_force_next_flush
 ------------------------
                         
@@ -706,10 +706,10 @@ pg_stat_force_next_flush
 step s1_track_funcs_all: SET track_functions = 'all';
 step s2_track_funcs_all: SET track_functions = 'all';
 step s2_begin: BEGIN;
-step s2_func_call: SELECT test_stat_func()
-test_stat_func
---------------
-              
+step s2_func_call_ifexists: SELECT test_stat_func_ifexists();
+test_stat_func_ifexists
+-----------------------
+                       
 (1 row)
 
 step s1_func_drop: DROP FUNCTION test_stat_func();
@@ -763,14 +763,12 @@ test_stat_func|                          |                |
 (1 row)
 
 
-starting permutation: s1_disable_debug_discard s2_disable_debug_discard s1_track_funcs_all s2_track_funcs_all s1_func_call s2_begin s2_func_call s1_func_drop s2_func_call s2_commit s2_ff s1_func_stats s2_func_stats
+starting permutation: s1_track_funcs_all s2_track_funcs_all s1_func_call s2_begin s2_func_call_ifexists s1_func_drop s2_func_call_ifexists s2_commit s2_ff s1_func_stats s2_func_stats
 pg_stat_force_next_flush
 ------------------------
                         
 (1 row)
 
-step s1_disable_debug_discard: SET debug_discard_caches = 0;
-step s2_disable_debug_discard: SET debug_discard_caches = 0;
 step s1_track_funcs_all: SET track_functions = 'all';
 step s2_track_funcs_all: SET track_functions = 'all';
 step s1_func_call: SELECT test_stat_func();
@@ -780,17 +778,17 @@ test_stat_func
 (1 row)
 
 step s2_begin: BEGIN;
-step s2_func_call: SELECT test_stat_func()
-test_stat_func
---------------
-              
+step s2_func_call_ifexists: SELECT test_stat_func_ifexists();
+test_stat_func_ifexists
+-----------------------
+                       
 (1 row)
 
 step s1_func_drop: DROP FUNCTION test_stat_func();
-step s2_func_call: SELECT test_stat_func()
-test_stat_func
---------------
-              
+step s2_func_call_ifexists: SELECT test_stat_func_ifexists();
+test_stat_func_ifexists
+-----------------------
+                       
 (1 row)
 
 step s2_commit: COMMIT;
@@ -829,14 +827,12 @@ test_stat_func|                          |                |
 (1 row)
 
 
-starting permutation: s1_disable_debug_discard s2_disable_debug_discard s1_track_funcs_all s2_track_funcs_none s1_func_call s2_begin s2_func_call s1_ff s1_func_stats s1_func_drop s2_track_funcs_none s1_func_stats s2_func_call s2_commit s2_ff s1_func_stats s2_func_stats
+starting permutation: s1_track_funcs_all s2_track_funcs_none s1_func_call s2_begin s2_func_call_ifexists s1_ff s1_func_stats s1_func_drop s2_track_funcs_none s1_func_stats s2_func_call_ifexists s2_commit s2_ff s1_func_stats s2_func_stats
 pg_stat_force_next_flush
 ------------------------
                         
 (1 row)
 
-step s1_disable_debug_discard: SET debug_discard_caches = 0;
-step s2_disable_debug_discard: SET debug_discard_caches = 0;
 step s1_track_funcs_all: SET track_functions = 'all';
 step s2_track_funcs_none: SET track_functions = 'none';
 step s1_func_call: SELECT test_stat_func();
@@ -846,13 +842,13 @@ test_stat_func
 (1 row)
 
 step s2_begin: BEGIN;
-step s2_func_call: SELECT test_stat_func()
-test_stat_func
---------------
-              
+step s2_func_call_ifexists: SELECT test_stat_func_ifexists();
+test_stat_func_ifexists
+-----------------------
+                       
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -888,10 +884,10 @@ name          |pg_stat_get_function_calls|total_above_zero|self_above_zero
 test_stat_func|                          |                |               
 (1 row)
 
-step s2_func_call: SELECT test_stat_func()
-test_stat_func
---------------
-              
+step s2_func_call_ifexists: SELECT test_stat_func_ifexists();
+test_stat_func_ifexists
+-----------------------
+                       
 (1 row)
 
 step s2_commit: COMMIT;
@@ -930,14 +926,12 @@ test_stat_func|                          |                |
 (1 row)
 
 
-starting permutation: s1_disable_debug_discard s2_disable_debug_discard s1_track_funcs_all s2_track_funcs_none s1_func_call s2_begin s2_func_call s1_ff s1_func_stats s1_func_drop s2_track_funcs_all s1_func_stats s2_func_call s2_commit s2_ff s1_func_stats s2_func_stats
+starting permutation: s1_track_funcs_all s2_track_funcs_none s1_func_call s2_begin s2_func_call_ifexists s1_ff s1_func_stats s1_func_drop s2_track_funcs_all s1_func_stats s2_func_call_ifexists s2_commit s2_ff s1_func_stats s2_func_stats
 pg_stat_force_next_flush
 ------------------------
                         
 (1 row)
 
-step s1_disable_debug_discard: SET debug_discard_caches = 0;
-step s2_disable_debug_discard: SET debug_discard_caches = 0;
 step s1_track_funcs_all: SET track_functions = 'all';
 step s2_track_funcs_none: SET track_functions = 'none';
 step s1_func_call: SELECT test_stat_func();
@@ -947,13 +941,13 @@ test_stat_func
 (1 row)
 
 step s2_begin: BEGIN;
-step s2_func_call: SELECT test_stat_func()
-test_stat_func
---------------
-              
+step s2_func_call_ifexists: SELECT test_stat_func_ifexists();
+test_stat_func_ifexists
+-----------------------
+                       
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -989,8 +983,12 @@ name          |pg_stat_get_function_calls|total_above_zero|self_above_zero
 test_stat_func|                          |                |               
 (1 row)
 
-step s2_func_call: SELECT test_stat_func()
-ERROR:  function call to dropped function
+step s2_func_call_ifexists: SELECT test_stat_func_ifexists();
+test_stat_func_ifexists
+-----------------------
+                       
+(1 row)
+
 step s2_commit: COMMIT;
 step s2_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
@@ -1053,7 +1051,7 @@ test_stat_func2
                
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -1243,7 +1241,7 @@ test_stat_func2
                
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -1360,7 +1358,7 @@ test_stat_func
               
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -1395,7 +1393,7 @@ test_stat_func
               
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -1430,7 +1428,7 @@ test_stat_func
               
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -1826,7 +1824,7 @@ test_stat_func
               
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -1915,7 +1913,7 @@ test_stat_func
               
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2004,7 +2002,7 @@ test_stat_func
               
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2093,7 +2091,7 @@ test_stat_func
               
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2152,7 +2150,7 @@ k3 |    1
 (4 rows)
 
 step s2_table_update_k1: UPDATE test_stat_tab SET value = value + 1 WHERE key = 'k1';
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2269,7 +2267,7 @@ k0 |    1
 (1 row)
 
 step s1_track_counts_off: SET track_counts = off;
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2307,7 +2305,7 @@ key|value
 k0 |    1
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2357,7 +2355,7 @@ k1 |    2
 (2 rows)
 
 step s1_track_counts_on: SET track_counts = on;
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2395,7 +2393,7 @@ k1 |    2
 (2 rows)
 
 step s1_table_update_k1: UPDATE test_stat_tab SET value = value + 1 WHERE key = 'k1';
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2451,7 +2449,7 @@ k1 |    2
 (2 rows)
 
 step s1_track_counts_on: SET track_counts = on;
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2489,7 +2487,7 @@ k1 |    2
 (2 rows)
 
 step s1_table_update_k1: UPDATE test_stat_tab SET value = value + 1 WHERE key = 'k1';
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2552,7 +2550,7 @@ k2 |    4
 k3 |    1
 (3 rows)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2615,7 +2613,7 @@ k2 |    4
 k3 |    1
 (3 rows)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2682,7 +2680,7 @@ key|value
 k0 |    1
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2743,7 +2741,7 @@ key|value
 k0 |    1
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2789,7 +2787,7 @@ step s1_table_insert_k1: INSERT INTO test_stat_tab(key, value) VALUES('k1', 1);
 step s1_table_update_k1: UPDATE test_stat_tab SET value = value + 1 WHERE key = 'k1';
 step s1_prepare_a: PREPARE TRANSACTION 'a';
 step s1_commit_prepared_a: COMMIT PREPARED 'a';
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2829,7 +2827,7 @@ step s1_table_insert_k1: INSERT INTO test_stat_tab(key, value) VALUES('k1', 1);
 step s1_table_update_k1: UPDATE test_stat_tab SET value = value + 1 WHERE key = 'k1';
 step s1_prepare_a: PREPARE TRANSACTION 'a';
 step s2_commit_prepared_a: COMMIT PREPARED 'a';
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2875,7 +2873,7 @@ step s1_table_insert_k1: INSERT INTO test_stat_tab(key, value) VALUES('k1', 1);
 step s1_table_update_k1: UPDATE test_stat_tab SET value = value + 1 WHERE key = 'k1';
 step s1_prepare_a: PREPARE TRANSACTION 'a';
 step s1_rollback_prepared_a: ROLLBACK PREPARED 'a';
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2915,7 +2913,7 @@ step s1_table_insert_k1: INSERT INTO test_stat_tab(key, value) VALUES('k1', 1);
 step s1_table_update_k1: UPDATE test_stat_tab SET value = value + 1 WHERE key = 'k1';
 step s1_prepare_a: PREPARE TRANSACTION 'a';
 step s2_rollback_prepared_a: ROLLBACK PREPARED 'a';
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2962,7 +2960,7 @@ step s1_table_update_k1: UPDATE test_stat_tab SET value = value + 1 WHERE key =
 step s1_table_drop: DROP TABLE test_stat_tab;
 step s1_prepare_a: PREPARE TRANSACTION 'a';
 step s1_rollback_prepared_a: ROLLBACK PREPARED 'a';
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -3003,7 +3001,7 @@ step s1_table_update_k1: UPDATE test_stat_tab SET value = value + 1 WHERE key =
 step s1_table_drop: DROP TABLE test_stat_tab;
 step s1_prepare_a: PREPARE TRANSACTION 'a';
 step s2_rollback_prepared_a: ROLLBACK PREPARED 'a';
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -3056,7 +3054,7 @@ pg_notify
          
 (3 rows)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
diff --git a/src/test/isolation/expected/stats_1.out b/src/test/isolation/expected/stats_1.out
index beb959453d..61fda0b502 100644
--- a/src/test/isolation/expected/stats_1.out
+++ b/src/test/isolation/expected/stats_1.out
@@ -33,7 +33,7 @@ test_stat_func
               
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -87,7 +87,7 @@ test_stat_func
               
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -174,7 +174,7 @@ test_stat_func
               
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -257,7 +257,7 @@ test_stat_func
               
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -360,7 +360,7 @@ test_stat_func
 (1 row)
 
 step s1_commit: COMMIT;
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -472,7 +472,7 @@ test_stat_func|                         2|t               |t
 (1 row)
 
 step s1_commit: COMMIT;
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -584,7 +584,7 @@ test_stat_func|                         2|t               |t
 (1 row)
 
 step s1_rollback: ROLLBACK;
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -619,7 +619,7 @@ test_stat_func|                         3|t               |t
 (1 row)
 
 
-starting permutation: s1_track_funcs_all s2_track_funcs_all s2_func_call s2_ff s2_begin s2_func_call s1_func_drop s1_func_stats s2_commit s2_ff s1_func_stats s2_func_stats
+starting permutation: s1_track_funcs_all s2_track_funcs_all s2_func_call s2_ff s2_begin s2_func_call_ifexists s1_func_drop s1_func_stats s2_commit s2_ff s1_func_stats s2_func_stats
 pg_stat_force_next_flush
 ------------------------
                         
@@ -640,10 +640,10 @@ pg_stat_force_next_flush
 (1 row)
 
 step s2_begin: BEGIN;
-step s2_func_call: SELECT test_stat_func()
-test_stat_func
---------------
-              
+step s2_func_call_ifexists: SELECT test_stat_func_ifexists();
+test_stat_func_ifexists
+-----------------------
+                       
 (1 row)
 
 step s1_func_drop: DROP FUNCTION test_stat_func();
@@ -697,7 +697,7 @@ test_stat_func|                          |                |
 (1 row)
 
 
-starting permutation: s1_track_funcs_all s2_track_funcs_all s2_begin s2_func_call s1_func_drop s1_func_stats s2_commit s2_ff s1_func_stats s2_func_stats
+starting permutation: s1_track_funcs_all s2_track_funcs_all s2_begin s2_func_call_ifexists s1_func_drop s1_func_stats s2_commit s2_ff s1_func_stats s2_func_stats
 pg_stat_force_next_flush
 ------------------------
                         
@@ -706,10 +706,10 @@ pg_stat_force_next_flush
 step s1_track_funcs_all: SET track_functions = 'all';
 step s2_track_funcs_all: SET track_functions = 'all';
 step s2_begin: BEGIN;
-step s2_func_call: SELECT test_stat_func()
-test_stat_func
---------------
-              
+step s2_func_call_ifexists: SELECT test_stat_func_ifexists();
+test_stat_func_ifexists
+-----------------------
+                       
 (1 row)
 
 step s1_func_drop: DROP FUNCTION test_stat_func();
@@ -763,14 +763,12 @@ test_stat_func|                          |                |
 (1 row)
 
 
-starting permutation: s1_disable_debug_discard s2_disable_debug_discard s1_track_funcs_all s2_track_funcs_all s1_func_call s2_begin s2_func_call s1_func_drop s2_func_call s2_commit s2_ff s1_func_stats s2_func_stats
+starting permutation: s1_track_funcs_all s2_track_funcs_all s1_func_call s2_begin s2_func_call_ifexists s1_func_drop s2_func_call_ifexists s2_commit s2_ff s1_func_stats s2_func_stats
 pg_stat_force_next_flush
 ------------------------
                         
 (1 row)
 
-step s1_disable_debug_discard: SET debug_discard_caches = 0;
-step s2_disable_debug_discard: SET debug_discard_caches = 0;
 step s1_track_funcs_all: SET track_functions = 'all';
 step s2_track_funcs_all: SET track_functions = 'all';
 step s1_func_call: SELECT test_stat_func();
@@ -780,17 +778,17 @@ test_stat_func
 (1 row)
 
 step s2_begin: BEGIN;
-step s2_func_call: SELECT test_stat_func()
-test_stat_func
---------------
-              
+step s2_func_call_ifexists: SELECT test_stat_func_ifexists();
+test_stat_func_ifexists
+-----------------------
+                       
 (1 row)
 
 step s1_func_drop: DROP FUNCTION test_stat_func();
-step s2_func_call: SELECT test_stat_func()
-test_stat_func
---------------
-              
+step s2_func_call_ifexists: SELECT test_stat_func_ifexists();
+test_stat_func_ifexists
+-----------------------
+                       
 (1 row)
 
 step s2_commit: COMMIT;
@@ -829,14 +827,12 @@ test_stat_func|                          |                |
 (1 row)
 
 
-starting permutation: s1_disable_debug_discard s2_disable_debug_discard s1_track_funcs_all s2_track_funcs_none s1_func_call s2_begin s2_func_call s1_ff s1_func_stats s1_func_drop s2_track_funcs_none s1_func_stats s2_func_call s2_commit s2_ff s1_func_stats s2_func_stats
+starting permutation: s1_track_funcs_all s2_track_funcs_none s1_func_call s2_begin s2_func_call_ifexists s1_ff s1_func_stats s1_func_drop s2_track_funcs_none s1_func_stats s2_func_call_ifexists s2_commit s2_ff s1_func_stats s2_func_stats
 pg_stat_force_next_flush
 ------------------------
                         
 (1 row)
 
-step s1_disable_debug_discard: SET debug_discard_caches = 0;
-step s2_disable_debug_discard: SET debug_discard_caches = 0;
 step s1_track_funcs_all: SET track_functions = 'all';
 step s2_track_funcs_none: SET track_functions = 'none';
 step s1_func_call: SELECT test_stat_func();
@@ -846,13 +842,13 @@ test_stat_func
 (1 row)
 
 step s2_begin: BEGIN;
-step s2_func_call: SELECT test_stat_func()
-test_stat_func
---------------
-              
+step s2_func_call_ifexists: SELECT test_stat_func_ifexists();
+test_stat_func_ifexists
+-----------------------
+                       
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -888,10 +884,10 @@ name          |pg_stat_get_function_calls|total_above_zero|self_above_zero
 test_stat_func|                          |                |               
 (1 row)
 
-step s2_func_call: SELECT test_stat_func()
-test_stat_func
---------------
-              
+step s2_func_call_ifexists: SELECT test_stat_func_ifexists();
+test_stat_func_ifexists
+-----------------------
+                       
 (1 row)
 
 step s2_commit: COMMIT;
@@ -930,14 +926,12 @@ test_stat_func|                          |                |
 (1 row)
 
 
-starting permutation: s1_disable_debug_discard s2_disable_debug_discard s1_track_funcs_all s2_track_funcs_none s1_func_call s2_begin s2_func_call s1_ff s1_func_stats s1_func_drop s2_track_funcs_all s1_func_stats s2_func_call s2_commit s2_ff s1_func_stats s2_func_stats
+starting permutation: s1_track_funcs_all s2_track_funcs_none s1_func_call s2_begin s2_func_call_ifexists s1_ff s1_func_stats s1_func_drop s2_track_funcs_all s1_func_stats s2_func_call_ifexists s2_commit s2_ff s1_func_stats s2_func_stats
 pg_stat_force_next_flush
 ------------------------
                         
 (1 row)
 
-step s1_disable_debug_discard: SET debug_discard_caches = 0;
-step s2_disable_debug_discard: SET debug_discard_caches = 0;
 step s1_track_funcs_all: SET track_functions = 'all';
 step s2_track_funcs_none: SET track_functions = 'none';
 step s1_func_call: SELECT test_stat_func();
@@ -947,13 +941,13 @@ test_stat_func
 (1 row)
 
 step s2_begin: BEGIN;
-step s2_func_call: SELECT test_stat_func()
-test_stat_func
---------------
-              
+step s2_func_call_ifexists: SELECT test_stat_func_ifexists();
+test_stat_func_ifexists
+-----------------------
+                       
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -989,8 +983,12 @@ name          |pg_stat_get_function_calls|total_above_zero|self_above_zero
 test_stat_func|                          |                |               
 (1 row)
 
-step s2_func_call: SELECT test_stat_func()
-ERROR:  function call to dropped function
+step s2_func_call_ifexists: SELECT test_stat_func_ifexists();
+test_stat_func_ifexists
+-----------------------
+                       
+(1 row)
+
 step s2_commit: COMMIT;
 step s2_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
@@ -1053,7 +1051,7 @@ test_stat_func2
                
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -1243,7 +1241,7 @@ test_stat_func2
                
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -1360,7 +1358,7 @@ test_stat_func
               
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -1395,7 +1393,7 @@ test_stat_func
               
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -1430,7 +1428,7 @@ test_stat_func
               
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -1827,7 +1825,7 @@ test_stat_func
               
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -1918,7 +1916,7 @@ test_stat_func
               
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2009,7 +2007,7 @@ test_stat_func
               
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2100,7 +2098,7 @@ test_stat_func
               
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2160,7 +2158,7 @@ k3 |    1
 (4 rows)
 
 step s2_table_update_k1: UPDATE test_stat_tab SET value = value + 1 WHERE key = 'k1';
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2277,7 +2275,7 @@ k0 |    1
 (1 row)
 
 step s1_track_counts_off: SET track_counts = off;
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2315,7 +2313,7 @@ key|value
 k0 |    1
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2365,7 +2363,7 @@ k1 |    2
 (2 rows)
 
 step s1_track_counts_on: SET track_counts = on;
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2403,7 +2401,7 @@ k1 |    2
 (2 rows)
 
 step s1_table_update_k1: UPDATE test_stat_tab SET value = value + 1 WHERE key = 'k1';
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2459,7 +2457,7 @@ k1 |    2
 (2 rows)
 
 step s1_track_counts_on: SET track_counts = on;
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2497,7 +2495,7 @@ k1 |    2
 (2 rows)
 
 step s1_table_update_k1: UPDATE test_stat_tab SET value = value + 1 WHERE key = 'k1';
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2560,7 +2558,7 @@ key|value
 k0 |    1
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2623,7 +2621,7 @@ key|value
 k0 |    1
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2692,7 +2690,7 @@ key|value
 k0 |    1
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2755,7 +2753,7 @@ key|value
 k0 |    1
 (1 row)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2803,7 +2801,7 @@ step s1_prepare_a: PREPARE TRANSACTION 'a';
 ERROR:  prepared transactions are disabled
 step s1_commit_prepared_a: COMMIT PREPARED 'a';
 ERROR:  prepared transaction with identifier "a" does not exist
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2845,7 +2843,7 @@ step s1_prepare_a: PREPARE TRANSACTION 'a';
 ERROR:  prepared transactions are disabled
 step s2_commit_prepared_a: COMMIT PREPARED 'a';
 ERROR:  prepared transaction with identifier "a" does not exist
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2893,7 +2891,7 @@ step s1_prepare_a: PREPARE TRANSACTION 'a';
 ERROR:  prepared transactions are disabled
 step s1_rollback_prepared_a: ROLLBACK PREPARED 'a';
 ERROR:  prepared transaction with identifier "a" does not exist
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2935,7 +2933,7 @@ step s1_prepare_a: PREPARE TRANSACTION 'a';
 ERROR:  prepared transactions are disabled
 step s2_rollback_prepared_a: ROLLBACK PREPARED 'a';
 ERROR:  prepared transaction with identifier "a" does not exist
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -2984,7 +2982,7 @@ step s1_prepare_a: PREPARE TRANSACTION 'a';
 ERROR:  prepared transactions are disabled
 step s1_rollback_prepared_a: ROLLBACK PREPARED 'a';
 ERROR:  prepared transaction with identifier "a" does not exist
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -3027,7 +3025,7 @@ step s1_prepare_a: PREPARE TRANSACTION 'a';
 ERROR:  prepared transactions are disabled
 step s2_rollback_prepared_a: ROLLBACK PREPARED 'a';
 ERROR:  prepared transaction with identifier "a" does not exist
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
@@ -3080,7 +3078,7 @@ pg_notify
          
 (3 rows)
 
-step s1_ff: SELECT pg_stat_force_next_flush(); RESET debug_discard_caches;
+step s1_ff: SELECT pg_stat_force_next_flush();
 pg_stat_force_next_flush
 ------------------------
                         
diff --git a/src/test/isolation/specs/stats.spec b/src/test/isolation/specs/stats.spec
index f27d11eede..be4ae1f4ff 100644
--- a/src/test/isolation/specs/stats.spec
+++ b/src/test/isolation/specs/stats.spec
@@ -14,6 +14,13 @@ setup
 
     CREATE TABLE test_slru_stats(slru TEXT, stat TEXT, value INT);
 
+    -- calls test_stat_func, but hides error if it doesn't exist
+    CREATE FUNCTION test_stat_func_ifexists() RETURNS VOID LANGUAGE plpgsql AS $$
+    BEGIN
+        PERFORM test_stat_func();
+    EXCEPTION WHEN undefined_function THEN
+    END;$$;
+
     SELECT pg_stat_force_next_flush();
 }
 
@@ -25,6 +32,7 @@ teardown
     DROP TABLE IF EXISTS test_stat_tab;
     DROP FUNCTION IF EXISTS test_stat_func();
     DROP FUNCTION IF EXISTS test_stat_func2();
+    DROP FUNCTION test_stat_func_ifexists();
 }
 
 session s1
@@ -32,7 +40,6 @@ setup { SET stats_fetch_consistency = 'none'; }
 step s1_fetch_consistency_none { SET stats_fetch_consistency = 'none'; }
 step s1_fetch_consistency_cache { SET stats_fetch_consistency = 'cache'; }
 step s1_fetch_consistency_snapshot { SET stats_fetch_consistency = 'snapshot'; }
-step s1_disable_debug_discard { SET debug_discard_caches = 0; }
 step s1_clear_snapshot { SELECT pg_stat_clear_snapshot(); }
 step s1_begin { BEGIN; }
 step s1_commit { COMMIT; }
@@ -42,7 +49,7 @@ step s1_commit_prepared_a { COMMIT PREPARED 'a'; }
 step s1_rollback_prepared_a { ROLLBACK PREPARED 'a'; }
 
 # Function stats steps
-step s1_ff { SELECT pg_stat_force_next_flush(); RESET debug_discard_caches; }
+step s1_ff { SELECT pg_stat_force_next_flush(); }
 step s1_track_funcs_all { SET track_functions = 'all'; }
 step s1_track_funcs_none { SET track_functions = 'none'; }
 step s1_func_call { SELECT test_stat_func(); }
@@ -118,9 +125,8 @@ step s1_slru_check_stats {
 
 
 session s2
-setup { SET stats_fetch_consistency = 'none'; RESET debug_discard_caches; }
+setup { SET stats_fetch_consistency = 'none'; }
 step s2_begin { BEGIN; }
-step s2_disable_debug_discard { SET debug_discard_caches = 0; }
 step s2_commit { COMMIT; }
 step s2_commit_prepared_a { COMMIT PREPARED 'a'; }
 step s2_rollback_prepared_a { ROLLBACK PREPARED 'a'; }
@@ -130,6 +136,7 @@ step s2_ff { SELECT pg_stat_force_next_flush(); }
 step s2_track_funcs_all { SET track_functions = 'all'; }
 step s2_track_funcs_none { SET track_functions = 'none'; }
 step s2_func_call { SELECT test_stat_func() }
+step s2_func_call_ifexists { SELECT test_stat_func_ifexists(); }
 step s2_func_call2 { SELECT test_stat_func2() }
 step s2_func_stats {
     SELECT
@@ -175,10 +182,12 @@ permutation
 
 ### Check interaction between dropping and stats reporting
 
-# Disable debug_discard_caches for a few of these tests - we precisely are
-# testing the behavior of no invalidations arriving.  "Real" invalidations
-# shouldn't trigger behavioral difference, because we are testing paths
-# precisely because they do not have AcceptInvalidationMessages calls.()
+# Some of these tests try to test behavior in cases where no invalidation
+# processing is triggered. To prevent output changes when
+# debug_discard_caches, CATCACHE_FORCE_RELEASE or RELCACHE_FORCE_RELEASE are
+# used (which trigger invalidation processing in paths that normally don't),
+# test_stat_func_ifexists() can be used, which tries to call test_stat_func(),
+# but doesn't raise an error if the function doesn't exist.
 
 # dropping a table remove stats iff committed
 permutation
@@ -193,14 +202,13 @@ permutation
 permutation
   s1_track_funcs_all s2_track_funcs_all
   s2_func_call s2_ff # this access increments refcount, preventing the shared entry from being dropped
-  s2_begin s2_func_call s1_func_drop s1_func_stats s2_commit s2_ff s1_func_stats s2_func_stats
+  s2_begin s2_func_call_ifexists s1_func_drop s1_func_stats s2_commit s2_ff s1_func_stats s2_func_stats
 permutation
   s1_track_funcs_all s2_track_funcs_all
-  s2_begin s2_func_call s1_func_drop s1_func_stats s2_commit s2_ff s1_func_stats s2_func_stats
+  s2_begin s2_func_call_ifexists s1_func_drop s1_func_stats s2_commit s2_ff s1_func_stats s2_func_stats
 permutation
-  s1_disable_debug_discard s2_disable_debug_discard
   s1_track_funcs_all s2_track_funcs_all
-  s1_func_call s2_begin s2_func_call s1_func_drop s2_func_call s2_commit s2_ff s1_func_stats s2_func_stats
+  s1_func_call s2_begin s2_func_call_ifexists s1_func_drop s2_func_call_ifexists s2_commit s2_ff s1_func_stats s2_func_stats
 
 # Function calls don't necessarily trigger cache invalidation processing. The
 # default handling of dropped stats could therefore end up with stats getting
@@ -209,13 +217,11 @@ permutation
 # on. Verify that the stats are indeed dropped, and document the behavioral
 # difference between track_functions settings.
 permutation
-  s1_disable_debug_discard s2_disable_debug_discard
   s1_track_funcs_all s2_track_funcs_none
-  s1_func_call s2_begin s2_func_call s1_ff s1_func_stats s1_func_drop s2_track_funcs_none s1_func_stats s2_func_call s2_commit s2_ff s1_func_stats s2_func_stats
+  s1_func_call s2_begin s2_func_call_ifexists s1_ff s1_func_stats s1_func_drop s2_track_funcs_none s1_func_stats s2_func_call_ifexists s2_commit s2_ff s1_func_stats s2_func_stats
 permutation
-  s1_disable_debug_discard s2_disable_debug_discard
   s1_track_funcs_all s2_track_funcs_none
-  s1_func_call s2_begin s2_func_call s1_ff s1_func_stats s1_func_drop s2_track_funcs_all s1_func_stats s2_func_call s2_commit s2_ff s1_func_stats s2_func_stats
+  s1_func_call s2_begin s2_func_call_ifexists s1_ff s1_func_stats s1_func_drop s2_track_funcs_all s1_func_stats s2_func_call_ifexists s2_commit s2_ff s1_func_stats s2_func_stats
 
 # test pg_stat_reset_single_function_counters
 permutation