Hi,
Could you point to some resource where I can read about two-phase
iterators in slightly more depth? There are still confusions for me as
to how exactly it works.
- Best
Parit
On 08/02/2016 07:07 PM, Andres de la Peña wrote:
Thanks Adrien, this is very helpful.
I have just read your blog post about this
<https://www.elastic.co/blog/better-query-execution-coming-elasticsearch-2-0>,
the two-phase iteration is really cool!
2016-07-31 20:17 GMT+01:00 Adrien Grand <jpou...@gmail.com>:
Lucene 5.0 introduced two-phase iteration
(see Scorer.twoPhaseIterator()) as a way to tackle slow queries. In short,
queries can be split into a fast approximation and a slower confirmation
and Lucene makes sure to reach agreement between the different
approximations of a BooleanQuery before checking the confirmations.
Both approximations and confirmations have an API that allows them to
expose a "cost" and the least costly components are always evaluated before
the most costly ones. So the filter strategy is not useful anymore, every
decision is made based on these cost APIs.
Le ven. 22 juil. 2016 à 15:32, Andres de la Peña <adelap...@stratio.com> a
écrit :
Hi all,
Suppose that we have a boolean query composed by two filtering queries,
where one of them is fast and the other is slow:
BooleanQuery.Builder builder = new BooleanQuery.Builder();
builder.add(fastQuery, FILTER);
builder.add(slowQuery, FILTER);
Query query = builder.build();
How is the intersection between the two sub-queries calculated? Is the
order in which they are added to the boolean query relevant? Is there
something we could do to take advantage of my knowledge about the
expected
performance of the sub-queries?
Prior to Lucene 6.0 there was a FilteredQuery.FilterStrategy providing
some
control about this. Is there something analogous in Lucene 6.0?
Thanks in advance,
--
Andrés de la Peña
Vía de las dos Castillas, 33, Ática 4, 3ª Planta
28224 Pozuelo de Alarcón, Madrid
Tel: +34 91 828 6473 // www.stratio.com // *@stratiobd
<https://twitter.com/StratioBD>*
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