Re: POC: Sharing record typmods between backends

On Wed, May 31, 2017 at 11:16 AM, Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:
> I agree with you. But, if I understand the use case correctly we need
> to store the TupleDesc for the RECORD in shared hash so that it can be
> shared across multiple processes. I think this can be achieved with
> the simplehash as well.
>
> For getting this done, we need some fixed shared memory for holding
> static members of SH_TYPE and the process which creates the simplehash
> will be responsible for copying these static members to the shared
> location so that other processes can access the SH_TYPE. And, the
> dynamic part (the actual hash entries) can be allocated using DSA by
> registering SH_ALLOCATE function.

Well, SH_TYPE's members SH_ELEMENT_TYPE *data and void *private_data
are not going to work in DSM, because they are pointers. You can
doubtless come up with a way around that problem, but I guess the
question is whether that's actually any better than just using DHT.

--
Robert Haas
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