Re: count(*) performance improvement ideas
От | Magnus Hagander |
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Тема | Re: count(*) performance improvement ideas |
Дата | |
Msg-id | 20080416093838.55834d92@mha-laptop обсуждение исходный текст |
Ответ на | Re: count(*) performance improvement ideas (Tom Lane <tgl@sss.pgh.pa.us>) |
Ответы |
Re: count(*) performance improvement ideas
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Список | pgsql-hackers |
Tom Lane wrote: > "Stephen Denne" <Stephen.Denne@datamail.co.nz> writes: > > From: Tom Lane [mailto:tgl@sss.pgh.pa.us] > >> As for 2) and 3), can't you look into the pg_settings view? > > > pg_settings view doesn't contain custom variables created on the > > fly, > > Really? [ pokes around ... ] Hm, you're right, because > add_placeholder_variable() sets the GUC_NO_SHOW_ALL flag, and in this > usage it'll never be cleared. I wonder if we should change that. > > The whole thing is a bit of an abuse of what the mechanism was > intended for, and so I'm not sure we should rejigger GUC's behavior > to make it more pleasant, but on the other hand if we're not ready to > provide a better substitute ... While I agree with that part, is there any actual *reason* why we shouldn't have the custom variables included in pg_settings? ISTM that it would be usable in cases that aren't an abuse as well... //Magnus
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