Re: Defer selection of asynchronous subplans until the executor initialization stage

On Wed, Apr 06, 2022 at 03:58:29PM +0900, Etsuro Fujita wrote:
> I have committed the patch after modifying it as such. (I think we
> can improve these later, if necessary.)

This patch seems to be causing the planner to crash.
Here's a query reduced from sqlsmith.

| explain SELECT 1 FROM information_schema.constraint_column_usage WHERE 1 <= pg_trigger_depth();

Program terminated with signal SIGSEGV, Segmentation fault.
#0 0x000055b4396a2edf in trivial_subqueryscan (plan=0x7f4219ed93b0) at ../../../../src/include/nodes/pg_list.h:151
151 return l ? l->length : 0;
(gdb) bt
#0 0x000055b4396a2edf in trivial_subqueryscan (plan=0x7f4219ed93b0) at ../../../../src/include/nodes/pg_list.h:151
#1 0x000055b43968af89 in mark_async_capable_plan (plan=plan(at)entry=0x7f4219ed93b0, path=path(at)entry=0x7f4219e89538) at createplan.c:1132
#2 0x000055b439691924 in create_append_plan (root=root(at)entry=0x55b43affb2b0, best_path=best_path(at)entry=0x7f4219ed0cb8, flags=flags(at)entry=0) at createplan.c:1329
#3 0x000055b43968fa21 in create_plan_recurse (root=root(at)entry=0x55b43affb2b0, best_path=best_path(at)entry=0x7f4219ed0cb8, flags=flags(at)entry=0) at createplan.c:421
#4 0x000055b43968f974 in create_projection_plan (root=root(at)entry=0x55b43affb2b0, best_path=best_path(at)entry=0x7f4219ed0f60, flags=flags(at)entry=1) at createplan.c:2039
#5 0x000055b43968fa6f in create_plan_recurse (root=root(at)entry=0x55b43affb2b0, best_path=0x7f4219ed0f60, flags=flags(at)entry=1) at createplan.c:433
#6 0x000055b439690221 in create_plan (root=root(at)entry=0x55b43affb2b0, best_path=<optimized out>) at createplan.c:348
#7 0x000055b4396a1451 in standard_planner (parse=0x55b43af05e28, query_string=<optimized out>, cursorOptions=2048, boundParams=0x0) at planner.c:413
#8 0x000055b4396a19c1 in planner (parse=parse(at)entry=0x55b43af05e28, query_string=query_string(at)entry=0x55b43af04c40 "SELECT 1 FROM information_schema.constraint_column_usage WHERE 1 > pg_trigger_depth();",
cursorOptions=cursorOptions(at)entry=2048, boundParams=boundParams(at)entry=0x0) at planner.c:277
#9 0x000055b439790c78 in pg_plan_query (querytree=querytree(at)entry=0x55b43af05e28, query_string=query_string(at)entry=0x55b43af04c40 "SELECT 1 FROM information_schema.constraint_column_usage WHERE 1 > pg_trigger_depth();",
cursorOptions=cursorOptions(at)entry=2048, boundParams=boundParams(at)entry=0x0) at postgres.c:883
#10 0x000055b439790d54 in pg_plan_queries (querytrees=0x55b43afdd528, query_string=query_string(at)entry=0x55b43af04c40 "SELECT 1 FROM information_schema.constraint_column_usage WHERE 1 > pg_trigger_depth();",
cursorOptions=cursorOptions(at)entry=2048, boundParams=boundParams(at)entry=0x0) at postgres.c:975
#11 0x000055b439791239 in exec_simple_query (query_string=query_string(at)entry=0x55b43af04c40 "SELECT 1 FROM information_schema.constraint_column_usage WHERE 1 > pg_trigger_depth();") at postgres.c:1169
#12 0x000055b439793183 in PostgresMain (dbname=<optimized out>, username=<optimized out>) at postgres.c:4542
#13 0x000055b4396e6af7 in BackendRun (port=port(at)entry=0x55b43af2ffe0) at postmaster.c:4489
#14 0x000055b4396e9c03 in BackendStartup (port=port(at)entry=0x55b43af2ffe0) at postmaster.c:4217
#15 0x000055b4396e9e4a in ServerLoop () at postmaster.c:1791
#16 0x000055b4396eb401 in PostmasterMain (argc=7, argv=<optimized out>) at postmaster.c:1463
#17 0x000055b43962b4df in main (argc=7, argv=0x55b43aeff0c0) at main.c:202

Actually, the original query failed like this:
#2 0x000055b4398e9f90 in ExceptionalCondition (conditionName=conditionName(at)entry=0x55b439a61238 "plan->scanstatus == SUBQUERY_SCAN_UNKNOWN", errorType=errorType(at)entry=0x55b43994b00b "FailedAssertion",
#3 0x000055b4396a2ecf in trivial_subqueryscan (plan=0x55b43b59cac8) at setrefs.c:1367