I was just approached with an optimizer question I cannot answer. Does
our optimizer know how expensive different comparisons are? That is can
it do something like:

If there are different comparisons in a where clause check the ints
first, then the strings, then everything with regexp, or like clauses
etc. and finally function calls at last, because in most cases a
function call is the most expensive one. 

Okay, we may argue whether a regexp is more expensive than a function,
but you get the idea. Are we able to get that logic in where clauses
where no index is defined? I just tried a query that given the order in
the where clause either takes a few seconds or forever. Well, I killed
the query after quite some time.

Michael Meskes
Go SF 49ers! Go Rhein Fire!
Use Debian GNU/Linux! Use PostgreSQL!

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