Re: unlogged tables vs. GIST

On Tue, Jan 15, 2013 at 1:58 PM, Heikki Linnakangas
<hlinnakangas(at)vmware(dot)com> wrote:
>> I think what Heikki had in mind was that the copy in the index would be
>> the authoritative one, not some image in shared memory. This'd imply
>> dirtying the root page on every insert, as well as increased contention
>> for the root page, so it might have performance problems.
>
> Not every insert, just every split. Which might still be a performance
> problem, but an order of magnitude smaller.

I think that might be acceptable from a performance point of view -
after all, if the index is unlogged, you're saving the cost of WAL -
but I guess I still prefer a generic solution to this problem (a
generalization of GetXLogRecPtrForTemp) rather than a special-purpose
solution based on the nitty-gritty of how GiST uses these values.
What's the difference between storing this value in pg_control and,
say, the OID counter?

--
Robert Haas
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