Re: Forcing use of specific index - Mailing list pgsql-performance

From William Yu
Subject Re: Forcing use of specific index
Date
Msg-id d7qooc$4pf$1@news.hub.org
Whole thread Raw
In response to Forcing use of specific index  (Tobias Brox <tobias@nordicbet.com>)
List pgsql-performance
A pretty awful way is to mangle the sql statement so the other field
logical statements are like so:

select * from mytable where 0+field = 100




Tobias Brox wrote:
> Is it any way to attempt to force the planner to use some specific index
> while creating the plan?  Other than eventually dropping all the other
> indices (which is obiously not a solution in production setting anyway)?
>
> I have one case where I have added 16 indices to a table, many of them
> beeing partial indices.  The table itself has only 50k of rows, but are
> frequently used in heavy joins.  I imagine there can be exponential order on
> the number of alternative paths the planner must examinate as function of
> the number of indices?
>
> It seems to me that the planner is quite often not choosing the "best"
> index, so I wonder if there is any easy way for me to check out what the
> planner think about a specific index :-)
>

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