Re: Planning a change of representation in the planner

Tom Lane kirjutas R, 07.02.2003 kell 06:35:
> I've been thinking of doing this for a while just on efficiency grounds,
> but kept putting it off because I don't expect much of any performance
> gain on simple queries. (You need a dozen or so tables in a query
> before the inefficiencies of the list representation really start to
> hurt.) But tonight I'm thinking I'll do it anyway, because it'll also
> be impervious to duplicate-element bugs.
>
> Comments?

Maybe the quicker way to avoid duplicate-element bugs (and get faster
merges) is to keep the lists ordered, so instead of just appending the
next int, you scan to the proper place and put it there (if it is not
there already).

Ordered lists are also much faster ( just O(N) ) to
compare/union/intersect.

--
Hannu Krosing <hannu(at)tm(dot)ee>