Re: More correlated (?) index woes

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От Melvin Davidson
Тема Re: More correlated (?) index woes
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Msg-id CANu8Fiw3om5RubbeV1Hzbrwq5dnWMSsU0vS-eau9UzosvdYO9Q@mail.gmail.com
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Ответ на Re: More correlated (?) index woes  (Geoff Winkless <pgsqladmin@geoff.dj>)
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On Tue, Mar 29, 2016 at 6:47 AM, Geoff Winkless <pgsqladmin@geoff.dj> wrote:
On 28 March 2016 at 20:23, I wrote:
Table pa has 7522676 rows, 4834042 of which have field1 NULL, so it's absolutely not reasonable to expect this to be an optimal strategy.
It occurred to me that even though the majority of values are NULL, there are ​
 
​1691 unique values in pa.field1, so I suppose it might seem more attractive to the planner than it should do (that's more unique values than there are scdate entries).

I might just set enable_seqscan to false and leave it at that. It makes me unhappy though.

Geoff



>I might just set enable_seqscan to false

Geoff, that has worked for me in the past. It forces the use of index if available, but if there is no suitable index, it will do a seq scan anyway, so there is low risk in doing that.

--
Melvin Davidson
I reserve the right to fantasize.  Whether or not you
wish to share my fantasy is entirely up to you.

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