Christian Schröder wrote:
Or would it be possible to tweak how the planner determines the
selectivity? I have read in the docs (chapter 54.1) that in case of
more than one condition in the where clause, independency is
assumed. In my case ("... where test like '11%' and test not like
'113%'") this is clearly not the case, so it might be an
interesting point to address.
I think the planner does think about the interactions of
inequalities, so if you can express your query with less-than and
friends, or even with BETWEEN, you might get a better plan. I don't
know the details of your setup, but you can do things like this with
any ordered type:
where test between '11' and '113'
or test >= '114'
I know this does not match the exact semantics of your query, but
hopefully you get the idea.
- John D. Burger
MITRE
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