Re: How to define template types in PostgreSQL

Hi!

I'd suggest creating an API that defines a general function set with
variable input,
and calling implementation defined on the input type?

On Sat, Jan 7, 2023 at 12:32 PM Esteban Zimanyi <esteban(dot)zimanyi(at)ulb(dot)be>
wrote:

> Dear all
>
> MobilityDB (https://github.com/MobilityDB/MobilityDB) defines at the C
> level four template types: Set, Span, SpanSet, and Temporal. The type Set
> is akin to PostgreSQL's ArrayType restricted to one dimension, but enforces
> the constraint that sets do not have duplicates, the types Span and SpanSet
> are akin to PostgreSQL's RangeType and MultirangeType but enforce the
> constraints that span types are of fixed length and that empty spans and
> infinite bounds are not allowed, and the typeTemporal is used to
> manipulate time-varying values.
>
> These template types need to be instantiated at the SQL level with base
> types (int, bigint, float, timestamptz, text, ...) and because of this,
> MobilityDB needs to define numerous SQL functions that all call the same
> function in C. Taking as example the Set type, we need to define, e.g.,
>
> CREATE FUNCTION intset_eq(intset, intset) RETURNS bool AS
> 'MODULE_PATHNAME', 'Set_eq' ...
> CREATE FUNCTION bigintset_eq(bigintset, bigintset) RETURNS bool AS
> 'MODULE_PATHNAME', 'Set_eq' ...
> CREATE FUNCTION floatset_eq(floatset, floatset) RETURNS bool AS
> 'MODULE_PATHNAME', 'Set_eq' ...
> CREATE FUNCTION textset_eq(textset, textset) RETURNS bool AS
> 'MODULE_PATHNAME', 'Set_eq' ...
> ...
>
> CREATE FUNCTION intset_ne(intset, intset) RETURNS bool AS
> 'MODULE_PATHNAME', 'Set_ne' ...
> CREATE FUNCTION bigintset_ne(bigintset, bigintset) RETURNS bool AS
> 'MODULE_PATHNAME', 'Set_ne' ...
> CREATE FUNCTION floatset_ne(floatset, floatset) RETURNS bool AS
> 'MODULE_PATHNAME', 'Set_ne' ...
> CREATE FUNCTION textset_ne(textset, textset) RETURNS bool AS
> 'MODULE_PATHNAME', 'Set_ne' ...
> ...
>
> In the case of arrays, ranges, and multiranges, PostgreSQL avoids this
> redundancy using pseudo-types such as anyarray, anyrange, anymultirange, ...
>
> Is there a possibility that we can also define pseudo types such as
> anyset, anyspan, anyspanset, anytemporal, .... ?
>
> This will considerably reduce the number of SQL functions to define.
> Currently, given the high number of functions in MobilityDB, creating the
> extension takes a loooong time ....
>
> Regards
>
> Esteban
>
>

--
Regards,
Nikita Malakhov
Postgres Professional
https://postgrespro.ru/