Re: [HACKERS] POC: Sharing record typmods between backends - Mailing list pgsql-hackers

From Andres Freund
Subject Re: [HACKERS] POC: Sharing record typmods between backends
Date
Msg-id 20170531174636.53sgh7thgfqeybqb@alap3.anarazel.de
Whole thread Raw
In response to Re: [HACKERS] POC: Sharing record typmods between backends  (Dilip Kumar <dilipbalaut@gmail.com>)
Responses Re: [HACKERS] POC: Sharing record typmods between backends  (Robert Haas <robertmhaas@gmail.com>)
List pgsql-hackers
On 2017-05-31 13:27:28 -0400, Dilip Kumar wrote:
> On Wed, May 31, 2017 at 12:53 PM, Robert Haas <robertmhaas@gmail.com> wrote:
> > 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.
> 
> Probably I misunderstood the question. I assumed that we need to bring
> in DHT only for achieving this goal. But, if the question is simply
> the comparison of DHT vs simplehash for this particular case then I
> agree that DHT is a more appropriate choice.

Yea, I don't think simplehash is the best choice here.  It's worthwhile
to use it for performance critical bits, but using it for everything
would just increase code size without much benefit.  I'd tentatively
assume that anonymous record type aren't going to be super common, and
that this is going to be the biggest bottleneck if you use them.

- Andres



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