Lucene / Elasticsearch is pretty much insignificant to this as long as you use filters. You should prefer not_analyzed fields with string values to represent those flags vs having dedicated boolean fields if you will have more than a few such flags.
-- Itamar Syn-Hershko http://code972.com | @synhershko <https://twitter.com/synhershko> Freelance Developer & Consultant Author of RavenDB in Action <http://manning.com/synhershko/> On Wed, Dec 10, 2014 at 10:22 AM, Dror Atariah <[email protected]> wrote: > Assume that I want to be able to flag documents in an index according to > their attributes: isFoo and isBar [1]. As far as I understand, there are > two approaches: > > 1) Use dedicated fields for the flags: If the document is a Foo then add a > field named isFoo. Similarly, for isBar. > 2) Use a flags field that will be an array of strings. In this case, if > the document is Foo then "flags" will contain the string "isFoo". > > What are the pros and cons in terms of space and runtime complexities? > > Bear in mind the following queries examples: Consider the case where one > wants to check the attributes of the documents in the index. In particular, > if I want to find the documents that are either Foo *or* Bar I can either > (a) In case (1): Use a Boolean "should" filter the surrounds two > "exists"'s filters checking whether either isFoo or isBar exist. > (b) In case (2): Use a single "exists" filter that checks the existence of > the field "flags". > > A different case, is if I want to find the documents that are both Foo > *and* Bar: > (a) In case (1): Like before, replace the "should" with a "must". > (b) In case (2): Surround two "term"s filters with a "must" Boolean one. > > Lastly, finding the documents that are Foo but *not* Bar. > > In the bottom line, In case (1) all queries boil down to mixture of > Boolean, exists and missing filters. In case (2), one has to process the > strings in the array of strings named "flags". My intuition is that it is > faster to use method (1). In terms of space complexity I believe there is > no difference. > > I'm looking forward to your insights! > Dror > > [1]: Obviously, there could be way more flags... > > -- > You received this message because you are subscribed to the Google Groups > "elasticsearch" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/elasticsearch/ef637057-4303-4c75-9bbf-ed72e0d4806b%40googlegroups.com > <https://groups.google.com/d/msgid/elasticsearch/ef637057-4303-4c75-9bbf-ed72e0d4806b%40googlegroups.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/elasticsearch/CAHTr4ZstGjg-b7tHX8R56sGB9_znBzDwnJO4naC6y_L6FaQ19g%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
