18/08/2017 17:40, Alvaro Herrera пишет:
> Ildar Musin wrote:
>
>> While we've been developing pg_pathman extension one of the most frequent
>> questions we got from our users was about global index support. We cannot
>> provide it within an extension. And I couldn't find any recent discussion
>> about someone implementing it. So I'm thinking about giving it a shot and
>> start working on a patch for postgres.
>>
>> One possible solution is to create an extended version of item pointer which
>> would store relation oid along with block number and position:
> I've been playing with the index code in order to allow indirect tuples,
> which are stored in a format different from IndexTupleData.
>
> I've been adding an "InMemoryIndexTuple" (maybe there's a better name)
> which internally has pointers to both IndexTupleData and
> IndirectIndexTupleData, which makes it easier to pass around the index
> tuple in either format. It's very easy to add an OID to that struct,
> which then allows to include the OID in either an indirect index tuple
> or a regular one.
>
> Then, wherever we're using IndexTupleData in the index AM code, we would
> replace it with InMemoryIndexTuple. This should satisfy both your use
> case and mine.
>
I found the thread about indirect indexes
(https://www.postgresql.org/message-id/20161018182843.xczrxsa2yd47pnru%40alvherre.pgsql),
but it seems that it haven't been updated for some time and I couldn't
find InMemoryIndexTuple in the latest patch. Is there a newer version?
Generally I think this may be a good idea.
--
Ildar Musin
Postgres Professional: http://www.postgrespro.com
Russian Postgres Company