| From: | Markus Schaber <schabi(at)logix-tt(dot)com> |
|---|---|
| To: | Andreas Joseph Krogh <andreak(at)officenet(dot)no> |
| Cc: | pgsql-sql(at)postgresql(dot)org |
| Subject: | Re: Constraint question |
| Date: | 2006-05-19 08:38:43 |
| Message-ID: | 446D8413.8060303@logix-tt.com |
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| Thread: | |
| Lists: | pgsql-sql |
Hi, Andreas,
Andreas Joseph Krogh wrote:
>>CREATE UNIQUE INDEX foo ON onp_crm_businessfield_company(company_id)
>>WHERE is_prefferred;
> I also figured out that an index like this also works:
> UNIQUE(company_id, is_preferred)
> This works because NULL = NULL is false. But I guess your solution is cleaner.
Yes, it works, but it needs more disk space (it has to index all rows,
and it needs to save both columns), and thus is slower, too.
HTH,
Markus
--
Markus Schaber | Logical Tracking&Tracing International AG
Dipl. Inf. | Software Development GIS
Fight against software patents in EU! www.ffii.org www.nosoftwarepatents.org
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