Re: pgsql: Assert(IsTransactionState()) in RelationIdGetRelation().

On 2014-02-06 16:28:23 +0000, Tom Lane wrote:
> Assert(IsTransactionState()) in RelationIdGetRelation().
>
> Commit 42c80c696e9c8323841180029cc62741c21bd356 added an
> Assert(IsTransactionState()) in SearchCatCache(), to catch
> any code that thought it could do a catcache lookup outside
> transactions. Extend the same idea to relcache lookups.

Hm, I am not sure if it works this way. In a patched postgres I just
got:
#2 0x00000000008b4b27 in ExceptionalCondition (conditionName=0xa90a78 "!(IsTransactionState())", errorType=0xa90708 "FailedAssertion",
fileName=0xa905c8 "/home/andres/src/postgresql/src/backend/utils/cache/relcache.c", lineNumber=1622)
at /home/andres/src/postgresql/src/backend/utils/error/assert.c:54
#3 0x00000000008a3fd6 in RelationIdGetRelation (relationId=1259) at /home/andres/src/postgresql/src/backend/utils/cache/relcache.c:1622
#4 0x00000000004a25ea in relation_open (relationId=1259, lockmode=1) at /home/andres/src/postgresql/src/backend/access/heap/heapam.c:1038
#5 0x00000000004a2898 in heap_open (relationId=1259, lockmode=1) at /home/andres/src/postgresql/src/backend/access/heap/heapam.c:1201
#6 0x00000000008a10ba in ScanPgRelation (targetRelId=2693, indexOK=1 '\001', suspend_snap=1 '\001')
at /home/andres/src/postgresql/src/backend/utils/cache/relcache.c:308
#7 0x00000000008a268c in RelationInitPhysicalAddr (relation=0x7fac2a842658)
at /home/andres/src/postgresql/src/backend/utils/cache/relcache.c:1019
#8 0x00000000008a4861 in RelationClearRelation (relation=0x7fac2a842658, rebuild=1 '\001')
at /home/andres/src/postgresql/src/backend/utils/cache/relcache.c:1949
#9 0x00000000008a4db5 in RelationFlushRelation (relation=0x7fac2a842658)
at /home/andres/src/postgresql/src/backend/utils/cache/relcache.c:2157
#10 0x00000000008a4ec7 in RelationCacheInvalidateEntry (relationId=2693)
at /home/andres/src/postgresql/src/backend/utils/cache/relcache.c:2209
#11 0x000000000089d7dc in LocalExecuteInvalidationMessage (msg=0xd53df0 <messages.8525+240>)
at /home/andres/src/postgresql/src/backend/utils/cache/inval.c:546
#12 0x000000000076fdc5 in ReceiveSharedInvalidMessages (invalFunction=0x89d6ef <LocalExecuteInvalidationMessage>,
resetFunction=0x89d930 <InvalidateSystemCaches>) at /home/andres/src/postgresql/src/backend/storage/ipc/sinval.c:127
#13 0x000000000089d9f9 in AcceptInvalidationMessages () at /home/andres/src/postgresql/src/backend/utils/cache/inval.c:640
#14 0x00000000004f12e1 in AtStart_Cache () at /home/andres/src/postgresql/src/backend/access/transam/xact.c:855
#15 0x00000000004f247c in StartTransaction () at /home/andres/src/postgresql/src/backend/access/transam/xact.c:1834
#16 0x00000000004f2f7a in StartTransactionCommand () at /home/andres/src/postgresql/src/backend/access/transam/xact.c:2507
#17 0x0000000000737827 in ReorderBufferCommit (rb=0x15cc568, xid=3170, commit_lsn=71557144, end_lsn=71557704, commit_time=445461926831965)
at /home/andres/src/postgresql/src/backend/replication/logical/reorderbuffer.c:1353

Obviously this isn't reproducable in core postgres the way it is here,
but it looks like it'd be possible:

static void
StartTransaction(void)
{
...

AtStart_GUC();
AtStart_Inval();
AtStart_Cache();
AfterTriggerBeginXact();

/*
* done with start processing, set current transaction state to "in
* progress"
*/
s->state = TRANS_INPROGRESS;
}

Not immediately sure how to handle this, except adding another state test
function allowing TRANS_START|INPROGRESS|COMMIT?

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
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