Re: check constraint question - Mailing list pgsql-general

From Tom Lane
Subject Re: check constraint question
Date
Msg-id 10870.1201189677@sss.pgh.pa.us
Whole thread Raw
In response to check constraint question  ("Tim Rupp" <caphrim007@gmail.com>)
Responses Re: check constraint question
List pgsql-general
"Tim Rupp" <caphrim007@gmail.com> writes:
> ... a bunch of inherited tables that have the following constraint

> CHECK (start_time >= '2008-01-01'::date AND end_time < '2008-01-01'::date)

> and when i do the same query (as in the documentation) on the table, I
> get a bunch of sequential scans in the planner, and it appears to
> ignore my constraints

> netflow=# explain SELECT count(*) FROM flows WHERE start_time >= DATE
> '2008-01-23' AND end_time < '2008-01-26'::date;

I don't think you've thought this through carefully.  That WHERE
condition is not inconsistent with that CHECK constraint, ie, there
could be some rows in the table that meet the WHERE.  In fact,
a set of constraints of this form don't represent a unique partitioning
do they?  (They might if you added the additional constraint that
start_time <= end_time, but that's not explicit here.)

            regards, tom lane

pgsql-general by date:

Previous
From: Bill Moran
Date:
Subject: Re: Getting all tables into memory
Next
From: User Map
Date:
Subject: change the default data directory