| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Bruce Momjian <bruce(at)momjian(dot)us> |
| Cc: | Ron Mayer <rm_pg(at)cheapcomplexdevices(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, Gregory Stark <stark(at)enterprisedb(dot)com>, pgsql-hackers(at)postgresql(dot)org, Andrew Dunstan <andrew(at)dunslane(dot)net>, Hans-Jürgen Schönig <postgres(at)cybertec(dot)at> |
| Subject: | Re: Mini improvement: statement_cost_limit |
| Date: | 2008-08-15 21:54:00 |
| Message-ID: | 10684.1218837240@sss.pgh.pa.us |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Bruce Momjian <bruce(at)momjian(dot)us> writes:
> Ron Mayer wrote:
>> Seems less fool-proof to me.
> My point is that people should _know_ they are using a cartesian
> product, and a warning would do that for users who have no need for a
> cartesian product and want to be warned about a possible error.
There are quite a lot of standard applications where small cartesian
products make sense --- star schemas are the traditional example.
I recall some discussions awhile back about how to persuade the planner
to consider such cases, in fact. Right now it'll generally use a series
of hash joins where maybe just one would be better.
I concur with Ron that the only merit of this proposal is that it's
(relatively) simple to implement.
regards, tom lane
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Robert Haas | 2008-08-15 22:03:40 | Re: Mini improvement: statement_cost_limit |
| Previous Message | Hannu Krosing | 2008-08-15 19:24:44 | Re: proposal sql: labeled function params |