Re: int8range and index usage for <@ operator

On Thu, 2022-04-28 at 12:57 -0400, Tom Lane wrote:
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> KOPOSOV Sergey <Sergey(dot)Koposov(at)ed(dot)ac(dot)uk> writes:
> > I'm trying to understand to is there a possibility to use an index for PG
> > when I have a integer column in a table and I want to execute queries with
> > this
> > integer_column <@ int8range
> > or
> > integer_column <@ int8multirange
> > in a where clause
>
> There's no support for that at the moment. In principle the range
> case could be converted to something like "integer_column >= lower_value
> AND integer_column <= upper_value" by attaching a support function to
> <@ and implementing the SupportRequestIndexCondition API. I think it
> could only work for a plan-time-constant range though, else you'd not know
> whether to use equality or inequality bounds. (Hmm ... or maybe, use
> equality always and treat it as a lossy conversion? But infinite bounds
> would still be a headache.)

Thanks for your reply. I will refresh my memory about support functions.

In my case I am certainly thinking of a situation where I'd like to do

integer_column <@ Some_Function()

where Some_function() is a a complicated C function returning a bunch of integer
ranges at runtime depending on arguments.

S

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