Обсуждение: postgresql bug?

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postgresql bug?

От
uwcssa
Дата:
i am using version 8.0.3<br /><br /> if you run the following query:<br /><br /> select count(*) from T1 where 
(T1.a>10and T1.a<20) or (T1.a>90 and T1.a<100)<br /><br /> the set_baserel_size_estimate will accurately
estimatethe selectivity on T1.<br /><br /> However, if you run<br /><br /> select count(*) from T1, T2 where T1.b=T2.c
and (T1.a>10 and T1.a<20) or (T1.a>90 and T1.a<100)<br /><br /> the selectivity estimate on T1 is always
1.0    the reason is the re-l->baserestrictinfo is NULL for the second query in set_baserel_size_estimates().<br
/><br/> is this a bug?<br />  <br />

Re: postgresql bug?

От
Tom Lane
Дата:
uwcssa <uwcssa@gmail.com> writes:
> select count(*) from T1, T2 where T1.b=3DT2.c and  (T1.a>10 and T1.a<20) or=
>  (
> T1.a>90 and T1.a<100)

> the selectivity estimate on T1 is always 1.0     the reason is the
> re-l->baserestrictinfo is NULL for the second query in
> set_baserel_size_estimates().

Sure you're not looking at T2?
        regards, tom lane