Standard DisMax does not fully support explicit AND/OR. You can prove that by trying to say q=fuel+OR+cell and see that the score stays the same (given mm=100%) It appears that DisMax does SOME intelligent handling of AND/OR/NOT, because it adds the "+" on the AND and a "-" on the NOT. But adding a "+" is redundant and does not change anything as long as mm=100%. The NOT actually seems to work, but the OR does not have any effect due to the "+" on the top-level ().
If you need boolean syntax support in DisMax, try the defType=edismax with patch SOLR-1553 or alternatively on branch_3x -- Jan Høydahl, search solution architect Cominvent AS - www.cominvent.com Training in Europe - www.solrtraining.com On 18. juni 2010, at 02.44, Erik Hatcher wrote: > Hmmm, maybe I'm wrong and it does support AND. Looking at the code I don't > see why it wouldn't, actually. Though I believe I've seen it documented that > it isn't supported (or at least not advertised to support). Ok, from the > dismax wiki page it says: "This query handler supports an extremely > simplified subset of the Lucene QueryParser syntax. Quotes can be used to > group phrases, and +/- can be used to denote mandatory and optional clauses". > Only special single characters are escaped. So AND/OR must work. Learn > something new every day! > > Erik > > > > On Jun 17, 2010, at 8:28 PM, Tommy Chheng wrote: > >> Thanks, Erik. that does work. I misunderstood the documentation, i thought >> "clause" meant "field" rather than the terms in the query. >> >> If dismax doesn't support the operator AND, why would the query >> "solr/select?q=fuel+cell" and "solr/select?q=fuel+AND+cell" get parsed >> differently(it adds the + for the AND query) and have different result count? >> >> @tommychheng >> Programmer and UC Irvine Graduate Student >> Find a great grad school based on research interests: >> http://gradschoolnow.com >> >> >> On 6/17/10 5:17 PM, Erik Hatcher wrote: >>> dismax does not support the operator AND. It uses +/- only. >>> >>> set mm=100% (not 1), as Hoss said, and try your query again. >>> >>> Erik >>> >>> On Jun 17, 2010, at 8:08 PM, Tommy Chheng wrote: >>> >>>> I don't think setting the mm helps. >>>> I have mm to 1 which means the query terms should be in at least one >>>> field. Both query strings satisfy this condition. >>>> >>>> The query "solr/select?q=fuel+cell" is parsed as >>>> >>>> "querystring":"fuel cell", >>>> "parsedquery":"+((DisjunctionMaxQuery((text:fuel | >>>> organization_name_ws_lc:fuel^5.0)) DisjunctionMaxQuery((text:cell | >>>> organization_name_ws_lc:cell^5.0)))~1) ()", >>>> "parsedquery_toString":"+(((text:fuel | organization_name_ws_lc:fuel^5.0) >>>> (text:cell | organization_name_ws_lc:cell^5.0))~1) ()", >>>> >>>> returns ~900 results >>>> >>>> The query "solr/select?q=fuel+AND+cell" is parsed as >>>> >>>> "querystring":"fuel AND cell", >>>> "parsedquery":"+(+DisjunctionMaxQuery((text:fuel | >>>> organization_name_ws_lc:fuel^5.0)) +DisjunctionMaxQuery((text:cell | >>>> organization_name_ws_lc:cell^5.0))) ()", >>>> "parsedquery_toString":"+(+(text:fuel | organization_name_ws_lc:fuel^5.0) >>>> +(text:cell | organization_name_ws_lc:cell^5.0)) ()", >>>> returns ~80 results >>>> >>>> (this is the behavior i want for query "fuel cell" because it adds the >>>> extra +). I want to do this without adding the AND for every query. >>>> >>>> >>>> >>>> @tommychheng >>>> Programmer and UC Irvine Graduate Student >>>> Find a great grad school based on research interests: >>>> http://gradschoolnow.com >>>> >>>> >>>> On 6/17/10 4:19 PM, Chris Hostetter wrote: >>>>> : I'm using the dismax request handler and want to set the default >>>>> operator to >>>>> : AND. >>>>> : Using the standard handler, i could just use the q.op or >>>>> defaultOperator in >>>>> : the schema, but this doesn't work using the dismax request handler. >>>>> : >>>>> : For example, if I call "solr/select/?q=fuel+cell", I want solr to >>>>> handle it as >>>>> : a "solr/select/?q=fuel+AND+cell" >>>>> >>>>> Please consult the dismax docs... >>>>> http://wiki.apache.org/solr/DisMaxRequestHandler#mm_.28Minimum_.27Should.27_Match.29 >>>>> >>>>> dismax uses the "mm" param to decide how clauses that don't have an >>>>> explicit operator will be dealt with -- the default is to require 100% of >>>>> the terms, so if you aren't seeing that behavior then you have a >>>>> solrconfig.xml that that sets the default mm value to something else. >>>>> >>>>> Starting with Solr 4.0 (and mybe 3.1 if it's backported) the default mm >>>>> will be based on the value of q.op (see SOLR-1889 for more details) >>>>> >>>>> >>>>> -Hoss >>>>> >>> >
