Re: Performance cost of a sort-merge join - Mailing list pgsql-general

From Yang Zhang
Subject Re: Performance cost of a sort-merge join
Date
Msg-id 9066fa251002220951q7ccf8f3enc5261c665bbc6edd@mail.gmail.com
Whole thread Raw
In response to Re: Performance cost of a sort-merge join  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-general
On Mon, Feb 22, 2010 at 12:10 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> I've left it running over night. By
>> comparison, a "select * from metarelcloud_transactionlog order by
>> transactionid" takes on the order of seconds/minutes (at least in
>> MySQL).
>
> That's got approximately nothing to do with this query.

Isn't that exactly what the leaf sorts are doing? By comparison,
"select * from metarelcloud_transactionlog order by transactionid"
takes much, much longer in PG (it's been running for 68 minutes now,
and still going, whereas MySQL took 6 minutes).
--
Yang Zhang
http://www.mit.edu/~y_z/

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