Re: [WDB-Development] wci.read on wdb2ts

[Michael O. A. <mic...@me...>]

> The reasoning seems sound to me, especially since we know that the
> boundary check is inaccurate. However, I would like to know more about
> the result the other optimizations: Last time I looked at the difference
> in performance between fetching a point and fetching a reference to an
> entire field was fairly small. If this is still true I believe the
> benefits from keeping the check may outweight the benefits of removing
> it.

This will not be the case; dropping the check for bounds in the join
generally reduces query execution time by an order of magnitude: <20 ms,
instead of 100-200 ms.

> Is it possible to run this in two steps? First use point specification
> to find the correct placeid(s), and then perform the select on
> wci_xxx.oidvalue? I guess this should make the planner happy.

We could run a function to filter the results of the SELECT, but that
would not make much sense, since the query extraction function already
does that. It can't be done before the SELECT, without adding a function
into the SELECT query with the attendant complications for the optimizer.

Regards,

Michael A.