Re: 7.4.xx regression

bs <bs@ionicsoft.com> writes:
> I have upgraded to version 7.4.0 (compiling the software and migrating
> the database using dump/restore)

> Now the following plan is produced

> Hash Join  (cost=17.08..42.15 rows=7 width=74)
>    Hash Cond: ("outer".id = "inner".entry)
>    ->  Seq Scan on cddb  (cost=0.00..20.00 rows=1000 width=74)
>    ->  Hash  (cost=17.07..17.07 rows=6 width=4)
>          ->  Index Scan using cddbentry1 on cddbentry  (cost=0.00..17.07
> rows=6 width=4)
>                Index Cond: (diskid = 'toto'::text)

> which result in a VERY much slower query as the cddb table has more than
> 1 million entry....  and there is at most one entry in cddbentry
> which matches the diskid !

> I think this can classified as a regression bug.

No, it can be classified as a "user forgot to vacuum or analyze"
mistake.  The estimates shown in the query plan look like the defaults
for an empty table.

            regards, tom lane