Re: GiST buffering build, bug in levelStep calculation
| От | Alexander Korotkov |
|---|---|
| Тема | Re: GiST buffering build, bug in levelStep calculation |
| Дата | |
| Msg-id | CAPpHfduK=enE+M2jRob5hvoLUtow=8DQY0dtNmRVrhc-PJEtXQ@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: GiST buffering build, bug in levelStep calculation (Tom Lane <tgl@sss.pgh.pa.us>) |
| Ответы |
Re: GiST buffering build, bug in levelStep calculation
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| Список | pgsql-hackers |
On Wed, May 30, 2012 at 12:25 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
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With best regards,
Alexander Korotkov.
Alexander Korotkov <aekorotkov@gmail.com> writes:Yeah, but if it could be *equal* to one, you've got a zero-divide there.
> 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.
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