PG Bug reporting form <noreply@postgresql.org> writes:
> The following query runs slow, as it seq scans tables, without using any
> index:
> select
> wp.id as id
> from
> web_page wp
> left join web_url_path url on wp.id=url.page
> order by
> url.priority asc
> limit 1
> I was expecting the "priority" column index would be used to retrieve first
> url then do a reverse join to get the corresponding page, and continue if no
> page is found.
It would probably do that if you used a plain join, or a right join.
But a nestloop plan cannot be driven from the inside of an outer join,
and that's the case this query presents.
regards, tom lane
