Re: unlogged tables vs. GIST

Robert Haas <robertmhaas@gmail.com> writes:
> On Tue, Dec 14, 2010 at 4:24 PM, Heikki Linnakangas
> <heikki.linnakangas@enterprisedb.com> wrote:
>> Hmm, the first idea that comes to mind is to use a counter like the
>> GetXLogRecPtrForTemp() counter I used for temp tables, but global, in shared
>> memory. However, that's a bit problematic because if we store a value from
>> that counter to LSN, it's possible that the counter overtakes the XLOG
>> insert location, and you start to get xlog flush errors. We could avoid that
>> if we added a new field to the GiST page header, and used that to store the
>> value in the parent page instead of the LSN.

> That doesn't seem ideal, either, because now you're eating up some
> number of bytes per page in every GIST index just on the off chance
> that one of them is unlogged.

On-disk compatibility seems problematic here as well.
        regards, tom lane