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[FWD] About "Our CLUSTER implementation is pessimal" patch

From: Leonardo F <m_lists(at)yahoo(dot)it>
To: pgsql-hackers(at)postgresql(dot)org
Subject: [FWD] About "Our CLUSTER implementation is pessimal" patch
Date: 2010-02-15 08:26:19
Message-ID: 993959.41681.qm@web29003.mail.ird.yahoo.com (view raw or flat)
Thread:
Lists: pgsql-hackers
I really thought this would have caused some interest, since

- this item is in the TODO list
- the improvement for CLUSTER in some scenarios is 800%,
and maybe more (if I didn't do anything wrong, of course...)

Could at least the message:
http://archives.postgresql.org/pgsql-hackers/2010-02/msg00766.php
be added to the TODO page, under 
"Improve CLUSTER performance by sorting to reduce
random I/O" ?
It would be sad if the patch got lost... 


Leonardo


> Attached the updated patch (should solve a bug) and a script.
> The sql scripts generates a 2M rows table ("orig"); then the
> table is copied and the copy clustered using seq + sort (since 
> "set enable_seqscan=false;").
> Then the table "orig" is copied again, and the copy clustered
> using regular index scan (set enable_indexscan=true; set 
> enable_seqscan=false).
> Then the same thing is done on a 5M rows table, and on a 10M
> rows table.
> 
> On my system (Sol10 on a dual Opteron 2.8) single disc:
> 
> 
> 2M:  seq+sort 11secs; regular index scan: 33secs
> 5M:  seq+sort 39secs; regular index scan: 105secs
> 10M:seq+sort 83secs; regular index scan: 646secs
> 
> 
> Maybe someone could suggest a better/different test?
> 
> 
> Leonardo



      

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