Re: optimisation for a table with frequently used query

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От Lew
Тема Re: optimisation for a table with frequently used query
Дата
Msg-id SeudncuAW8ZfscHbnZ2dnUVZ_ualnZ2d@comcast.com
обсуждение исходный текст
Ответ на Re: optimisation for a table with frequently used query  (PFC <lists@peufeu.com>)
Ответы Re: optimisation for a table with frequently used query  ("Dann Corbit" <DCorbit@connx.com>)
Список pgsql-general
danmcb wrote:
>> SELECT * from my_table where id_1 = x and id_2 = y;
>> Neither id_1 or id_2 or the combination of them is unique. I expect
>> this table to become large over time.

PFC wrote:
> Create an index on (id_1, id_2), or (id_2,id_1).

What are the strengths and weaknesses compared to creating two indexes, one on
each column?

I am guessing that changes to the table are slower with two indexes.  How
could it affect queries?

What if the typical query pattern was more balanced among constraints on one
column, on the other, and on both?

--
Lew

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