Ben wrote:
>> When you insert a tuple, it needs to be inserted into the index, yes.
>> There
>> is no way an insert can cause a sequential scan, except by some trigger
>> defined on the table.
>
> Actually, as it happens, there *is* a trigger defined on the table to
> fire before insert, but it too uses an index scan, at least according to
> explain. Though, you'd think if it actually was using an index scan,
> that would be showing up in pg_stat_user_tables, which it isn't. Might
> the fact that the trigger is a plpgsql function be throwing it off and
> keeping it from using more recent planner stats?
The query-plan for the function will be compiled first time it is
called. From that point on, it is fixed. It seems that is the source of
your seq-scans.
You can use the EXECUTE statement to construct a dynamic version of the
query, which will be planned every time it is run.
--
Richard Huxton
Archonet Ltd
