On Wed, May 30, 2012 at 12:25 AM, Tom Lane <t...@sss.pgh.pa.us> wrote:
> Alexander Korotkov <aekorot...@gmail.com> writes: > > On Tue, May 29, 2012 at 11:42 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > >> While I'm looking at this, is the first test involving > >> effective_cache_size bulletproof either? In particular, is > >> avgIndexTuplesPerPage clamped to be strictly greater than 1? > > > It's based on collected statistics on already inserted tuple sizes. Since > > tuple sizes are measured after possible toasting, I don't see the way > > for avgIndexTuplesPerPage to be less than 1. > > Yeah, but if it could be *equal* to one, you've got a zero-divide there. > avgIndexTuplesPerPage is calculated as: avgIndexTuplesPerPage = pageFreeSpace / itupAvgSize; I think size of each index tuple must be at least few times lower than pageFreeSpace to let us create any index. ------ With best regards, Alexander Korotkov.
