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#1 (**permalink**) 04-10-2008, 07:41 AM

Good morning,

We are at Postgres 7.4.5. I have encountered inaccuracies

after reindexing related to the statistics posted back to the PG_CLASS
table

For instance:

1. We have a 'queues' table with 6 indexes. We are at 110,000 rows in
this table.

When I reindex, the RELPAGE count decreases as expected but the
RELTUPLE

Count increases to about 132,000 in all indexes. I check and there
are still

Only 110,000 rows on the table.

2. We have a table that is quite volatile in its numbers, ranging from 100
to 6 million rows.

Last week we were at 50,000 rows but PG_CLASS.RELTUPLES showed 6
million for

The indexes. I reindexed and, again the RELPAGES count went down but
the RELTUPLES

Number went down to just 3 million.

Again a count after reindex gave the actual row count at 52,000.

Does anybody have any insight why this is happening and what I can do in the
short term?

I know we are at a back-leveled version so perhaps the long-term answer is
to upgrade.

Thank you,

Mark Steben

Senior DBA - AutoRevenue

Direct dial phone number: 413-327-3045

Please visit our new website at www.autorevenue.com
<http://www.autorevenue.com/>

"We do all the work.... you make all the money"

#2 (**permalink**) 04-10-2008, 07:41 AM

"Mark Steben" <msteben@autorevenue.com> writes:
> We are at Postgres 7.4.5. I have encountered inaccuracies
> after reindexing related to the statistics posted back to the PG_CLASS
> table

reindex enters the exact number of tuples indexed into
pg_class.reltuples. If there are more than you expect, that says there
are some dead-but-not-removable tuples in the relation. Check for old
open transactions that might still be able to see old versions of rows.

VACUUM VERBOSE should report the same number of unremovable rows BTW.

regards, tom lane

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REINDEX question