| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Sean Chittenden <sean(at)chittenden(dot)org> |
| Cc: | Jan Wieck <JanWieck(at)Yahoo(dot)com>, PostgreSQL Bugs List <pgsql-bugs(at)postgresql(dot)org>, Juris Krumins <juriskr(at)komin(dot)lv> |
| Subject: | Re: [GENERAL] cache lookup of relation 165058647 failed |
| Date: | 2004-05-04 05:55:23 |
| Message-ID: | 465.1083650123@sss.pgh.pa.us |
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| Lists: | pgsql-bugs pgsql-general |
Sean Chittenden <sean(at)chittenden(dot)org> writes:
> But, I am suspecting that it's a race condition with the new background
> writer code.
Why? Have you demonstrated that the failure does not occur in 7.4?
> psql:test-end2.sql:3: ERROR: cache lookup failed for relation 398033
> CONTEXT: SQL query "SELECT TRUE FROM pg_catalog.pg_class c LEFT JOIN
> pg_catalog.pg_namespace n ON n.oid = c.relnamespace WHERE c.relname =
> 'tmptbl'::TEXT AND c.relkind = 'r'::TEXT AND
> pg_catalog.pg_table_is_visible(c.oid)"
I think that pg_table_is_visible() will inspect the catalogs using
SnapshotNow semantics, while the above query will feed it with OIDs that
were valid under a start-of-query snapshot. So I'd expect failures in
any recent PG version, if tables are being dynamically created/deleted
by concurrent transactions.
regards, tom lane
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