Re: possible patch to increase number of hash overflow pages?

> It looks (from the hash algorithm code) as if the system is possibly
> needing more splitpoints than can be accomodated by the HashMetaPageData
> structure, rather than running out of overflow pages, because the error
> message that I'm getting is when the "splitnum" variable is greater than
> NCACHED, the latter being the array bound for the hashm_spares[] element
> of the HashMetaPageData structure. From src/backend/access/hashovfl.c:
>
> #define OVMSG "HASH: Out of overflow pages. Out of luck.\n"
>
> if (offset > SPLITMASK)
> {
> if (++splitnum >= NCACHED)
> elog(ERROR, OVMSG);
> metap->OVFL_POINT = splitnum;
> metap->SPARES[splitnum] = metap->SPARES[splitnum - 1];
> metap->SPARES[splitnum - 1]--;
> offset = 0;
> }
>
> So that's why I bumped the number of bits (in the OverflowPageAddress
> type) assigned to keep track of splitpoints to 8 bits.

If you want to work on the hash stuff, let us know. We are looking for
someone to do performance testing and debugging on hash indexes.

--
Bruce Momjian | http://candle.pha.pa.us
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