Re: Avoiding tuple construction/deconstruction during joining

Tom Lane wrote:

>=?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
>
>
Tom, thank you and the others for help. I'm glad that my problem can
help PostgreSQL improve and that there are people like you that
understand each little bit of the software :-)

Miroslav