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Re: Hash Aggregate plan picked for very large table == out of memory - Mailing list pgsql-general

From Mason Hale
Subject Re: Hash Aggregate plan picked for very large table == out of memory
Date
Msg-id 8bca3aa10706141409oa6ddc6fk305b446f45229bba@mail.gmail.com
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In response to Re: Hash Aggregate plan picked for very large table == out of memory  ("Mason Hale" <masonhale@gmail.com>)
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I should have mentioned this previously: running the same query against the same data on 8.1.5 does not result in a hash aggregate plan or an out of memory error. (Note: the hardware is different but very similar -- the main difference is the 8.1.9 server (with the error) has faster disks)

On 6/14/07, Mason Hale <masonhale@gmail.com> wrote:
Thanks Tom. Here's more info:

What have you got work_mem set to?  

40960

What's the actual number of groups
(target_page_id values)?

Approximately 40 million (I'll have a more precise number when the query finishes running ).

Maybe this helps?

crystal=> select null_frac, n_distinct, correlation from pg_stats where tablename = 'page_page_link' and attname = 'target_page_id';
 null_frac | n_distinct | correlation
-----------+------------+-------------
         0 |     550017 |    0.240603
(1 row)

Mason



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