>Please send to pgsql-hackers --- I'd like to get more eyeballs on this.
>There's no personally identifiable information here except that you've
>got a table named temp_queue that you've repeatedly TRUNCATEd or
>CLUSTERed or some such (likely the former since the reltuples counts
>are all zero). It'd be useful to know exactly what you were doing
>with it, though.
>
> regards, tom lane
More info as requested....
TEMP_QUEUE is used continously throughout the day (for some reason which
i chose not to use a normal temp table) data is grouped and inserted
from other tables, before being processed, and you are right the table
is then truncated before repeating - this happens at least once a minute
throughout the day..
After restarted following the pg_resetxlog, i noticed that the
temp_queue table was missing (had been created a day ago). I couldn't
select from it and had problems trying to recreate it (bits seemed to
exist already). I couldn't see it in pg_class or the other catalogs, but
after selecting to ignore the presumably corrupt indexes it appeared so
i manually removed the references (I've since learned about the -P
option to the server which may have helped here). The corruption in
pg_class manifested itself as multiple rows (for this and another table)
with the same OIDs
So not sure at what point what if anything got corrupted and what my
subsequent actions did to compound this..
Thanks
John Lister wrote:
Originally in psql-admin, but copied here at the request of Tom to..
Story so far, transaction log archiving went wrong causing the
transaction log disk to fill up. Foolishly i deleted the unarchived
transaction logs (early monday morning) which required a pg_resetxlog
to get the db up and running again. Since then we've had some minor db
corruption which has been fixed (mainly duplicate primary keys) except
for the pg_class table.
If i do a vacuum full on pg_class i get something like this:
INFO: vacuuming "pg_catalog.pg_class"INFO: "pg_class": found 37
removable, 1845 nonremovable row versions in 18905 pages
DETAIL: 27 dead row versions cannot be removed yet.
Nonremovable row versions range from 160 to 229 bytes long.
There were 933834 unused item pointers.
Total free space (including removable row versions) is 150368692 bytes.
18839 pages are or will become empty, including 0 at the end of the
table.
0 pages containing 0 free bytes are potential move destinations.
CPU 0.01s/0.05u sec elapsed 0.17 sec.INFO: index "pg_class_oid_index"
now contains 1813 row versions in 7 pages
DETAIL: 56 index row versions were removed.
0 index pages have been deleted, 0 are currently reusable.
CPU 0.00s/0.00u sec elapsed 0.00 sec.INFO: index
"pg_class_relname_nsp_index" now contains 1818 row versions in 24 pages
DETAIL: 63 index row versions were removed.
0 index pages have been deleted, 0 are currently reusable.
CPU 0.00s/0.00u sec elapsed 0.00 sec.WARNING: index
"pg_class_relname_nsp_index" contains 1818 row versions, but table
contains 1813 row versions
HINT: Rebuild the index with REINDEX.INFO: analyzing
"pg_catalog.pg_class"INFO: "pg_class": scanned 3000 of 18905 pages,
containing 227 live rows and 6 dead rows; 227 rows in sample, 1430
estimated total rows
Total query runtime: 4469 ms.
As you can see there are non-removable dead rows (which slowly grows)
and the table size is also increasing in size.. A reindex on the
indexes mentions also succeeds but another vacuum reports the same
thing...
In the log files the relevant bits are:
GMT LOG: relation "pg_class" TID 15538/4: dead HOT-updated tuple ---
cannot shrink relation
2009-02-12 21:06:40 GMT STATEMENT: VACUUM FULL VERBOSE ANALYZE pg_class
2009-02-12 21:06:40 GMT WARNING: index "pg_class_relname_nsp_index"
contains 1818 row versions, but table contains 1813 row versions
and finally the last message in the psql-admin thread suggested
dumping the above page, which is attached before.
Hmm. The comments in vacuum.c about this case suppose that it could
only be a transient condition, ie the tuple became dead while we were
looking at the page. Evidently it's persistent for you, which means
that for some reason heap_page_prune() is failing to remove an
already-dead tuple. I suspect this implies a corrupt HOT chain, but
maybe the data is okay and what you've got is really a bug in
heap_page_prune.
Could you send a dump of page 15538 of pg_class, using pg_filedump?
The source code for it is here:
http://sources.redhat.com/rhdb/utilities.html
Best would be -i -f format, ie
pg_filedump -i -f -R 15538 $PGDATA/base/something/1259
regards, tom lane
Any help would be appreciated as the pg_class table is constantly
growing which i'm guessing is going to start to affect performance
fairly soon. I'd like to avoid a full restore from backup if possible.
Thanks
JOHN
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