| From: | "Vadim B(dot) Mikheev" <vadim(at)sable(dot)krasnoyarsk(dot)su> |
|---|---|
| To: | David Gould <dg(at)illustra(dot)com> |
| Cc: | Michal Mosiewicz <mimo(at)interdata(dot)com(dot)pl>, pgsql-hackers(at)postgreSQL(dot)org |
| Subject: | Re: [HACKERS] Optimizer fails? |
| Date: | 1998-03-30 02:38:08 |
| Message-ID: | 351F058F.CA40DEA0@sable.krasnoyarsk.su |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
David Gould wrote:
>
> > Now, let's note, that there has been only a few IO transfers by now. No
> > more than few pages. And we have tupple identifiers pointing us to 64
> > records. Now we may sort this tids in ascending order to optimise IO.
>
> But, we do not do this tid sort. It really isn't easy as you might have
> millions of tids, not just a few. Which would mean doing an external sort.
> This might be a nice thing to do, but it isn't there now as far as I know.
Using TID as (last) part of index key is on my TODO.
This will speed up vacuuming, get rid of all duplicate key
problems and give us feature above.
> To scan the index to get the tids for keys 0...63 will take two page
> reads: root page, leaf1.
+ meta page read first - to get root page block number.
Vadim
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Vadim B. Mikheev | 1998-03-30 03:19:13 | Re: [HACKERS] Reminder: Indices are not used |
| Previous Message | Vadim B. Mikheev | 1998-03-30 00:37:09 | Re: Let's talk up 6.3 |