Re: Error when setting default_text_search_config

I wrote:
> I can reproduce a segfault on my Arch machine with 17.0, but only by
> also connecting to that database afterwards:
>
> postgres=# create database regress;
> postgres=# alter database regress set default_text_search_config to 'german';
> postgres=# \c regress
> connection to server at "localhost" (::1), port 15432 failed: server closed the connection unexpectedly
> This probably means the server terminated abnormally
> before or while processing the request.

Here's better backtrace based on commit fee8cb9473 (not sure why the
first one lacked the additional info):

#0 0x0000654521e03394 in MemoryContextReset (context=0x0) at mcxt.c:388
#1 0x0000654521a165ea in spcache_init () at namespace.c:318
#2 0x0000654521a16d46 in cachedNamespacePath (searchPath=0x654541b0f3f0 "\"$user\", public", roleid=10) at namespace.c:4234
#3 recomputeNamespacePath () at namespace.c:4294
#4 0x0000654521a19d45 in get_ts_config_oid (names=0x654541b86860, missing_ok=missing_ok(at)entry=true) at namespace.c:3162
#5 0x0000654521dd5f88 in check_default_text_search_config (newval=0x7ffcb598c928, extra=<optimized out>, source=PGC_S_DATABASE) at ts_cache.c:621
#6 0x0000654521dee440 in call_string_check_hook (conf=conf(at)entry=0x65452215e830 <ConfigureNamesString+11600>, newval=newval(at)entry=0x7ffcb598c928, extra=extra(at)entry=0x7ffcb598c930, source=source(at)entry=PGC_S_DATABASE, elevel=elevel(at)entry=19) at guc.c:6890
#7 0x0000654521df10fb in parse_and_validate_value (record=0x65452215e830 <ConfigureNamesString+11600>, name=0x654541b86468 "default_text_search_config", value=<optimized out>, source=PGC_S_DATABASE, elevel=19, newval=0x7ffcb598c928, newextra=0x7ffcb598c930) at guc.c:3260
#8 0x0000654521df202a in set_config_with_handle (name=name(at)entry=0x654541b86468 "default_text_search_config", handle=handle(at)entry=0x0, value=value(at)entry=0x654541b867a0 "german", context=context(at)entry=PGC_SUSET, source=source(at)entry=PGC_S_DATABASE, srole=10, action=GUC_ACTION_SET, changeVal=<optimized out>, elevel=19, is_reload=false) at guc.c:4010
#9 0x0000654521df65c5 in set_config_option (name=0x654541b86468 "default_text_search_config", value=0x654541b867a0 "german", context=<optimized out>, source=<optimized out>, action=<optimized out>, changeVal=true, elevel=0, is_reload=false) at guc.c:3363
#10 ProcessGUCArray (array=<optimized out>, context=PGC_SUSET, source=PGC_S_DATABASE, action=GUC_ACTION_SET) at guc.c:6438
#11 0x0000654521a274d7 in ApplySetting (snapshot=snapshot(at)entry=0x654541b855e8, databaseid=databaseid(at)entry=40965, roleid=roleid(at)entry=0, relsetting=relsetting(at)entry=0x7be2b87866e8, source=source(at)entry=PGC_S_DATABASE) at pg_db_role_setting.c:256
#12 0x0000654521dea2d6 in process_settings (databaseid=40965, roleid=10) at postinit.c:1342
#13 InitPostgres (in_dbname=in_dbname(at)entry=0x654541aeff60 "regress", dboid=<optimized out>, dboid(at)entry=0, username=username(at)entry=0x654541b2db98 "ewie", useroid=useroid(at)entry=0, flags=1, out_dbname=out_dbname(at)entry=0x0) at postinit.c:1217
#14 0x0000654521c9e8a6 in PostgresMain (dbname=0x654541aeff60 "regress", username=0x654541b2db98 "ewie") at postgres.c:4324
#15 0x0000654521c9a9df in BackendMain (startup_data=<optimized out>, startup_data_len=<optimized out>) at backend_startup.c:105
#16 0x0000654521c0acdb in postmaster_child_launch (child_type=child_type(at)entry=B_BACKEND, startup_data=startup_data(at)entry=0x7ffcb598cfe0 "", startup_data_len=startup_data_len(at)entry=4, client_sock=client_sock(at)entry=0x7ffcb598d000) at launch_backend.c:277
#17 0x0000654521c0e7a9 in BackendStartup (client_sock=0x7ffcb598d000) at postmaster.c:3593
#18 ServerLoop () at postmaster.c:1674
#19 0x0000654521c104bd in PostmasterMain (argc=argc(at)entry=4, argv=argv(at)entry=0x654541aedea0) at postmaster.c:1372
#20 0x000065452194ab33 in main (argc=4, argv=0x654541aedea0) at main.c:197

InitPostgres calls process_settings before InitializeSearchPath, and so
SearchPathCacheContext is null. Not sure how to fix this because
InitPostgres clearly states this before calling InitializeSearchPath:

/*
* Initialize various default states that can't be set up until we've
* selected the active user and gotten the right GUC settings.
*/

Maybe just don't use the cache in that case? For example,
check_search_path uses the cache only if SearchPathCacheContext is
initialized.

--
Erik