Re: Slow Delete : Seq scan instead of index scan

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On 10/16/2012 03:50 PM, Sylvain CAILLET wrote:
Hi to all,

I've got a trouble with some delete statements. My db contains a little
more than 10000 tables and runs on a dedicated server (Debian 6 - bi
quad - 16Gb - SAS disks raid 0). Most of the tables contains between 2
and 3 million rows and no foreign keys exist between them. Each is
indexed (btree) on start_date / end_date fields (bigint). The Postgresql
server has been tuned (I can give modified values if needed).

I perform recurrent DELETE upon a table subset (~1900 tables) and each
time, I delete a few lines (between 0 and 1200). Usually it takes
between 10s and more than 2mn. It seems to me to be a huge amount of
  time ! An EXPLAIN ANALYZE on a DELETE shows me that the planner uses a
Seq Scan instead of an Index Scan.

Can you post that (or paste to explain.depesz.com and link to it here) along with a "\d tablename" from psql?

--
Craig Ringer


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