Re: Slow query performance on large table

Andreas Pflug wrote:

> Tom,
>
> does this mean that a primary key alone might not be enough? As far as I
> understood Paul, the PK looks quite as the newly created index does, so
> "create index ind_meas on measurement (assessment,time)" should perform
> the same as "... primary key(assessment,time)".
> Do possibly non-optimal indices (only assessment, only time as Paul
> described earlier) screw up the optimizer, igoring the better option
> usiing the PK? Obviously, the index used should be combined of
> (assessment,time) but IMHO a PK should be enough.
>
> regards,
>
> Andreas
You are right - primary key should be ok, but Paul lost it. psql \d
shows primary key indexes, but in this case there was no such primary key.

Regards,
Tomasz Myrta