On Wed, May 30, 2012 at 12:25 AM, Tom Lane
<tgl@sss.pgh.pa.us> wrote:
Alexander Korotkov <
aekorotkov@gmail.com> writes:
> On Tue, May 29, 2012 at 11:42 PM, Tom Lane <
tgl@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.
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.