Re: GEQO threshold results

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От Bruce Momjian
Тема Re: GEQO threshold results
Дата
Msg-id 199903071202.HAA15795@candle.pha.pa.us
обсуждение исходный текст
Список pgsql-hackers
> You asked me to re-do the tests I had run to check the GEQO
> threshold.  With today's sources I get these runtimes:
> 
> # Tables:        7    8    9    10    11
> 
> std, with indexes    1.89    2.26    5.41    24.21    90.04
> GEQO, with indexes    3.73    6.98    16.98    43.81*    21.45
> std, no indexes        1.60    1.79    4.78    15.75    84.17
> GEQO, no indexes    3.30    6.04    15.52    18.73    22.35
> 
> So, (a) the number of indexes is still not very relevant,
> and (b) it looks like we oughta kick over to GEQO at 11 tables.
> 
> WHat were we at before?  6 or 8 I think?  Nice job :-)
> 
>             regards, tom lane
> 
> * That number is obviously out of line ... probably it was
> skewed by some other activity on my system at the time.
> I'm too lazy to repeat the measurement however.
> 

Done.  Thanks for doing the checking.

Doesn't seem like much of an increase, but it is N!, so I guess it is:
> 6!        720> 8!        40320> 11!        39916800


--  Bruce Momjian                        |  http://www.op.net/~candle maillist@candle.pha.pa.us            |  (610)
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