Re: ORDER BY costs

Jan Dittmer <jdittmer(at)sfhq(dot)hn(dot)org> escreveu: What is your work_mem setting? I think the default is 1MB which is
probably too low as your trying to sort roughly 150000*100Bytes = 15MB.

Jan

I think you would like to say 150000*896Bytes... Am I right? My default work_mem is 2048 and I changed to 200000... and pgsql_tmp directory is not used any more...but...

Now the new numbers:

Sort (cost=132929.22..133300.97 rows=148701 width=896) (actual time=3949.663..4029.618 rows=167710 loops=1)
Sort Key: anocalc, cadastro, codvencto, parcela
-> Index Scan using pk_arript, pk_arript, pk_arript, pk_arript on arript (cost=0.00..120154.28 rows=148701 width=896) (actual time=0.166..829.260 rows=167710 loops=1)
Index Cond: (((anocalc = 2005::numeric) AND (cadastro = 19::numeric) AND (codvencto = 0::numeric) AND (parcela >= 0::numeric)) OR ((anocalc = 2005::numeric) AND (cadastro = 19::numeric) AND (codvencto > 0::numeric)) OR ((anocalc = 2005::numeric) AND (cadastro > 19::numeric)) OR (anocalc > 2005::numeric))
Total runtime: 4184.723 ms
(5 rows)

It is less than with work_mem set to 2000 but is it worthly? I´m afraind of swapping... are not those settings applied for all backends?

Benkendorf

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