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