: Is there a way to run a subquery in Lucene, i.e. running a query only on
: the result of a first query to avoid scanning the whole index ?
: Is is worth forwarding this request to the developers, do you think it
: is feasible to implement such a short circuit operator where the term is
: "late" evaluated only if the expression to the left evaluates to true to
: avoid scanning the index in its entirety ?
As Uwe said, The problem is with the wildcard suffix. ... still.
It doesn't matter wether the term scanning is early or late -- the full
term enum (for that field) has to be scanned at least once no matter what.
The only possible optimization gained by doing a "late" scan of those
terms would be if the other mandatory clauses ("field1:foo" in your
example) didn't match any documents at all, then there would certianly be
a benefit in not doing the scan, but i'm not sure if it's worth the eextra
effor for that special case...
: > : Basically for queries such as field1:foo AND field2:*bar, I think it
consider the situation where "field1:foo" only matches a single document
X, and imagine you have the changed the code so that iterating the terms
for "field2:*bar" you are describing, so no term enumeration is done on
field2 doesn't happen unless absolutely neccessary. As soon as field1:foo
matches on document X, we still have to enumerate every term on field2
looking to see if that term also matches against document X -- we can't
even stop once we find a matching term, because the scoring model may want
to score that clause higher if multiple terms with the suffice "bar" match
against document X.
Right?
So i'm pretty sure that even though it might be possible to optimize the
edge case of no matching documents, i'm not sure if that optimization
would slow down hte more common case.
-Hoss
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