Re: Bitmap index scans use of filters on available columns

2015-11-04 Antonin Houska :

> While prefix expression
>
> y like 'abc%'
>
> can be converted to
>
> y >= 'abc'
>
> (see expand_indexqual_opclause()), I'm not sure any kind of expansion is
> possible for '%abc%' which would result in a b-tree searchable condition.

I think the question is not about using the b-tree for checking the
condition, but about just retrieving the value for y from the index,
and just using that to check the condition before fetching the
corresponding tuple from the heap.

Nicolas

-- 
A. Because it breaks the logical sequence of discussion.
Q. Why is top posting bad?