| From: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
|---|---|
| To: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
| Cc: | Gavin Sherry <swm(at)alcove(dot)com(dot)au>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Planning aggregates which require sorted or distinct |
| Date: | 2007-01-20 12:18:15 |
| Message-ID: | 20070120121815.GN26080@alvh.no-ip.org |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Simon Riggs wrote:
> I'm working on modifying Tuplestore that will allow you to store the
> last N tuples, rather than all previous input. This is specifically
> designed to allow Merge Join to do Mark/Restore without materializing
> the whole sort set. This can also be used to materialize Windows (i.e.
> <window clause> in SQL:2003), so you can store the current row plus n
> PRECEDING and/or n FOLLOWING rows as appropriate.
Interesting. This could also be used to implement the "partial sort"
stuff that Oleg is so interested in, and in which I believe Greg Stark
was also interested.
--
Alvaro Herrera http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Gavin Sherry | 2007-01-20 12:54:51 | Re: Planning aggregates which require sorted or distinct |
| Previous Message | Magnus Hagander | 2007-01-20 11:17:04 | Re: O_DIRECT support for Windows |