Re: Gin index on array of uuid - Mailing list pgsql-hackers
Ok, I think this is close as you point out.
I can see the GIN (2742 pg_am oid - access method) op classes defined explicitly for a lot of the core types in pg_opclass.h.
I can also see various GIN operator functions defined in pg_proc ("select proname, proargtypes from pg_proc where proname like '%extract%' " and many comparison functions "select proname, proargtypes from pg_proc where proname like '%cmp%' ").
It seems one way to do this is to add the missing remaining built in types such as UUID to pg_opclass.h.... but I am missing how this "DATA(insert(...))" operator class definition links to the four GIN functions (&&, @>, <@ and =). Is there a separate table or definition responsible for this linking?
Taking _timestamp_ops as an example:
DATA(insert ( 2742 _timestamp_ops PGNSP PGUID 2745 1115 t 1114 ));
How does postgresql determine the GIN function bindings? Where does this function pointer resolution occur?
Thank you,
Enrique
On Tue, Jun 21, 2016 at 12:20 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
Enrique MailingLists <enrique.mailing.lists@gmail.com> writes:
> Currently creating an index on an array of UUID involves defining an
> operator class. I was wondering if this would be a valid request to add as
> part of the uuid-ossp extension? This seems like a reasonable operator to
> support as a default for UUIDs.
This makes me itch, really, because if we do this then we should logically
do it for every other add-on type.
It seems like we are not that far from being able to have just one GIN
opclass on "anyarray". The only parts of this declaration that are
UUID-specific are the comparator function and the storage type, both of
which could be gotten without that much trouble, one would think.
> Any downsides to adding this as a default?
Well, it'd likely break things at dump/reload time for people who had
already created a competing "default for _uuid" opclass manually. I'm not
entirely sure, but possibly replacing the core opclasses with a single one
that is "default for anyarray" could avoid such failures. We'd have to
figure out ambiguity resolution rules.
regards, tom lane
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