Re: Slow query: bitmap scan troubles

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От Philip Scott
Тема Re: Slow query: bitmap scan troubles
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Msg-id 098101cdd24d$892524c0$9b6f6e40$@foo.me.uk
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Ответ на Re: Slow query: bitmap scan troubles  (Claudio Freire <klaussfreire@gmail.com>)
Список pgsql-performance
> The difference between cost estimation and actual cost of your queries,
under relatively precise row estimates, seems to suggest your e_c_s or r_p_c
aren't a reflection of your hardware's performance.

Wow, so tweaking these has fixed it and then some. It now picks a slightly
different plan than the 'fast' one previously:

New super fast version with e_c_s 6GB->88Gb and r_p_c 2-> 1 (s_p_c 1->0.5):
http://explain.depesz.com/s/ECk

For reference:
> Slow version with bitmapscan enabled: http://explain.depesz.com/s/6I7
> Fast version with bitmapscan disabled: http://explain.depesz.com/s/4MWG



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