| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Miroslav Šulc <miroslav(dot)sulc(at)startnet(dot)cz> |
| Cc: | pgsql-hackers(at)postgreSQL(dot)org, pgsql-performance(at)postgreSQL(dot)org |
| Subject: | Re: Avoiding tuple construction/deconstruction during joining |
| Date: | 2005-03-14 19:22:35 |
| Message-ID: | 29030.1110828155@sss.pgh.pa.us |
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| Lists: | pgsql-hackers pgsql-performance |
=?windows-1250?Q?Miroslav_=8Aulc?= <miroslav(dot)sulc(at)startnet(dot)cz> writes:
> seriously, I am far below this level of knowledge. But I can contribute
> a test that (maybe) can help. I have rewritten the query so it JOINs the
> varchar() fields (in fact all fields except the IDPK) at the last INNER
> JOIN. Though there is one more JOIN, the query is more than 5 times
> faster (1975.312 ms) :-)
That confirms my thought that passing the data up through multiple
levels of join is what's killing us. I'll work on a solution. This
will of course be even less back-patchable to 8.0.* than Ogawa's work,
but hopefully it will fix the issue for 8.1.
regards, tom lane
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