Hi everyone,
I've noticed that truncating mapped catalogs causes the server to
crash due to an assertion failure. Here are the details:
Executing below commands:
-- set allow_system_table_mods TO on;
-- truncate table pg_type;
Results into a server crash with below backtrace:
...
#2 0x000055736767537d in ExceptionalCondition
(conditionName=0x5573678c5760 "relation->rd_rel->relkind ==
RELKIND_INDEX", fileName=0x5573678c4b28 "relcache.c",
lineNumber=3896) at assert.c:66
#3 0x0000557367664e31 in RelationSetNewRelfilenumber
(relation=0x7f68240f1d58, persistence=112 'p') at relcache.c:3896
#4 0x000055736715b952 in ExecuteTruncateGuts
(explicit_rels=0x55736989e5b0, relids=0x55736989e600,
relids_logged=0x0, behavior=DROP_RESTRICT, restart_seqs=false,
run_as_table_owner=false) at tablecmds.c:2146
#5 0x000055736715affa in ExecuteTruncate (stmt=0x55736989f950) at
tablecmds.c:1877
#6 0x0000557367493693 in standard_ProcessUtility
(pstmt=0x55736989fa00, queryString=0x55736989eed0 "truncate table
pg_type;", readOnlyTree=false,
context=PROCESS_UTILITY_TOPLEVEL, params=0x0, queryEnv=0x0,
dest=0x5573698a0330, qc=0x7ffe19367ac0) at utility.c:728
As seen from the backtrace above, the assertion failure occurs in
'RelationSetNewRelfilenumber()' at:
if (RelationIsMapped(relation))
{
/* This case is only supported for indexes */
Assert(relation->rd_rel->relkind == RELKIND_INDEX);
}
I would like to know why we are only expecting index tables here and
not the regular catalog tables. For instance, pg_type is a mapped
relation but not of index type, leading to the failure in this case.
Should we consider changing this Assert condition from RELKIND_INDEX
to (RELKIND_INDEX || RELKIND_RELATION)?
Additionally, is it advisable to restrict truncation of the pg_class
table? It's like a kind of circular dependency in case of pg_class
which is not applicable in case of other catalog tables.
--
With Regards,
Ashutosh Sharma.
