Re: Gist indexes on int arrays

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От Greg Stark
Тема Re: Gist indexes on int arrays
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Msg-id 87smu3kv7d.fsf@stark.dyndns.tv
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Ответ на Re: Gist indexes on int arrays  (Achilleus Mantzios <achill@matrix.gatewaynet.com>)
Ответы Re: Gist indexes on int arrays  (Achilleus Mantzios <achill@matrix.gatewaynet.com>)
Re: Gist indexes on int arrays  (Greg Stark <gsstark@mit.edu>)
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Achilleus Mantzios <achill@matrix.gatewaynet.com> writes:

> Moreover if your array element positions that you want to compare
> against(e.g attr_a[1], or attr_b[n], where n is the last element) are
> known, then you could have a function "first" that returns
> the first element ...

Except that's precisely what I'm *not* doing. I'm treating the arrays as sets
and looking for records where the set contains a given value. This is a
denormalized table generated nightly from fully normalized raw data.

So to simplify it, the query might have clauses like:

WHERE foo_id = 900 AND '{5}'::integer[] ~ attribute_set_array

Right now I have a btree index on (foo_id).

Can I have a GiST index on (foo_id, attribute_set_array) and have it be just
as fast at narrowing the search to just foo_id = 900 but also speed up the ~
operation?

Incidentally, it seems odd that there isn't an operator like ~ but optimized
specifically for searching for a single item. It seems awkward and possibly
unnecessarily slow to have to construct an array for the search parameter
every time.

--
greg



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