"Leif B. Kristensen" <[EMAIL PROTECTED]> writes:
> Can anybody tell me why the following query requires a full table scan?
> pgslekt=> explain select person_id, last_edit from persons
>                order by last_edit desc, person_id desc limit 50;

> 'persons' is a regular table where person_id is the primary 
> key. 'last_edit' is a regular date field. I've also tried:
> pgslekt=> create index last_edit_key on persons(last_edit);
> But that doesn't make any difference.

Neither of those indexes can provide the requested two-column ordering.

                        regards, tom lane

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