[Zope] ZCTextIndex - prefix wildcards not supported?
Dieter Maurer
dieter at handshake.de
Sat Nov 22 12:58:48 EST 2003
Andreas Jung wrote at 2003-11-22 09:07 +0100:
> > Dieter Maurer wrote:
> > ...
> > The standard way to support so called "left truncation" is to build
> > a mapping "R" "s.reverse() --> s" for each word "s" in your index.
> > With this map, "left truncation" can be mapped to "right truncation"
> > as you use your reversed pattern to scan through "R"s keys.
> >
> > This still does not support truncation on both sides: to make this
> > efficiently, you need sub-word indexes.
>
> Truncation can be achived very easily by performing a range search
> on BTrees....very evil but it works!.
For patterns of the form "*subword*" (I spoke about
truncation on both sides) there is no initial range to retrict the search
to (that's why it is inefficient ;-)).
Neither is for patterns of the form "*subword" unless you have
the "reverse" mapping, I mentioned above.
--
Dieter
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