Re: Gist indexes on int arrays

On 4 Mar 2003, Greg Stark wrote:

> 
> 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?

I am afraid you cant do that easily. (but you can follow recent 
discussions on the matter).
int4 does not have an opclass that can cope with "gist".

> 
> 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.
> 

What do you mean by "slow"?

> --
> greg
> 

-- 
==================================================================
Achilleus Mantzios
S/W Engineer
IT dept
Dynacom Tankers Mngmt
Nikis 4, Glyfada
Athens 16610
Greece
tel:    +30-210-8981112
fax:    +30-210-8981877
email:  achill@matrix.gatewaynet.com       mantzios@softlab.ece.ntua.gr