| From: | "Steinar H(dot) Gunderson" <sgunderson(at)bigfoot(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | pgsql-performance(at)postgresql(dot)org, Teodor Sigaev <teodor(at)sigaev(dot)ru>, Oleg Bartunov <oleg(at)sai(dot)msu(dot)su> |
| Subject: | Re: [GENERAL] Creation of tsearch2 index is very slow |
| Date: | 2006-01-21 00:36:46 |
| Message-ID: | 20060121003646.GA31406@uio.no |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-general pgsql-performance |
On Fri, Jan 20, 2006 at 07:23:10PM -0500, Tom Lane wrote:
> I'm not very clear on what tsearch2 is doing with these bitmaps, but it
> looks like an upper page's downlink has the union (bitwise OR) of the
> one-bits in the values on the lower page, and you have to visit the lower
> page if this union has a nonempty intersection with the set you are looking
> for. If that's correct, what you really want is to divide the values so
> that the unions of the two sets have minimal overlap ... which seems to me
> to have little to do with what the code does at present.
Sort of like the vertex-cover problem? That's probably a lot harder than
finding the two farthest points...
/* Steinar */
--
Homepage: http://www.sesse.net/
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Keary Suska | 2006-01-21 01:20:22 | Re: How to fetch rows with multiple values |
| Previous Message | Tom Lane | 2006-01-21 00:23:10 | Re: [GENERAL] Creation of tsearch2 index is very slow |
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Craig A. James | 2006-01-21 01:30:17 | Re: [GENERAL] Creation of tsearch2 index is very slow |
| Previous Message | Tom Lane | 2006-01-21 00:23:10 | Re: [GENERAL] Creation of tsearch2 index is very slow |