Uff... I See.. thx dir the explanation :) Am 30.11.2017 3:13 nachm. schrieb "Emir Arnautović" < emir.arnauto...@sematext.com>:
> Hi Faraz, > It is a bit worse than that - it also needs to calculate score, so for > each matching doc of one query part it has to check if it appears in > results of other query parts. If you use term query parser, you avoid > calculating score - all doc will have score 1. > Solr is based on lucene, which is mainly inverted index: > https://en.wikipedia.org/wiki/Inverted_index <https://en.wikipedia.org/ > wiki/Inverted_index> so knowing that helps understand how expensive some > queries are. It is relatively easy to figure out what steps are needed for > different query types. Of course, Lucene includes a lot smartness, and it > is probably not using the naive approach, but it cannot avoid limitations > of inverted index. > > HTH, > Emir > -- > Monitoring - Log Management - Alerting - Anomaly Detection > Solr & Elasticsearch Consulting Support Training - http://sematext.com/ > > > > > On 30 Nov 2017, at 02:39, Faraz Fallahi <faraz.fall...@googlemail.com> > wrote: > > > > Hi Toke, > > > > Just to be clear and to understand. Does this mean that a query of the > form > > author:name1 OR author:name2 OR author:name3 > > > > Is being processed like e.g. > > > > 1 query against the index with author:name1 getting 4 result > > Then 1 query against the index with author:name2 getting 3 result > > Then 1 query against the index with author:name3 getting 1 result > > > > And in the end all results are merged and i get a result of 8 ? > > > > So a query of thousand authors will be splitted into thousand single > > queries against the index? > > > > Do i understand this correctly? > > > > Thx for the help > > Faraz > > > > > > Am 28.11.2017 15:39 schrieb "Toke Eskildsen" <t...@kb.dk>: > > > > On Tue, 2017-11-28 at 11:07 +0100, Faraz Fallahi wrote: > >> I have a question regarding solr queries. > >> My query basically contains thousand of OR conditions for authors > >> (author:name1 OR author:name2 OR author:name3 OR author:name4 ...) > >> The execution time on my index is huge (around 15 sec). When i tag > >> all the associated documents with a custom field and value like > >> authorlist:1 and then i change my query to just search for > >> authorlist:1 it executes in 78 ms. How come there is such a big > >> difference in exec-time? > > > > Due to the nature of inverted indexes (which lies at the heart of > > Solr), your thousands of OR-queries means thousands of lookups, whereas > > your authorlist means a single lookup. Adding to this the results for > > each author needs to be merged with the other author-results - for > > authorlist the results are there directly. > > > > If your author lists are static, indexing them as you did in your test > > is the best solution. > > > > If they are not static, using a filter-query will ensure that they are > > at least cached subsequently, so that only the first call will be > > slow. > > > > If they are semi-static and there are not too many of them, you could > > do warm-up filter-queries for all the different groups so that the > > users does not pay the first-call penalty. This requires your filter- > > cache to be large enough to hold all the author lists. > > > > - Toke Eskildsen, Royal Danish Library > >
