SOLR / Lucene MultiFieldQueryParser - solr

I wish to query a Lucene index and ask the question "..does the string ABC occur in Field A AND string DEF in Field B ..."
BOTH conditions (ABC in Field A and DEF in Field B) must be true ....I've fooled around
with a few searches and don't seem to be hit the proper combination.
Any ideas / examples ...seems that the MultiFieldQueryParser may be the answer but I've had no luck so far.

The standard query parser supports this sort of query, like:
+fielda:ABC +fieldb:DEF
The + character is the required operator, so this query will require a match on both fielda:ABC and fieldb:XYZ.
See the query parser syntax documentation, for more information.
MultiFieldQueryParser is used to automatically search for the same content in multiple fields, so not quite what you are looking for.

Turns out on a SOLR browser search, the q.OP=AND on the URL will provide the ANDING condition I was looking for.

Related

Solr OR query on a text field

How to perform a simple query on a text field with an OR condition? Something like name:ABC OR name:XYZ so the resulting set would contain only those docs where name is exactly "XYZ" or "ABC"
Dug tons of manuals, cannot figure this out.
I use Solr 5.5.0
Update: Upgraded to Solr 6.6.0, still cannot figure it out. Below are illustrations to demonstrate my issue:
This works:
This works too:
This still works:
But this does not! Omg why!?
There are many ways to perform OR query. Below I have listed some of them. You can select any of it.
[Simple Query]
q=name:(XYZ OR ABC)
[Lucene Query Parser]
q={!lucene q.op=OR df=name v="XYZ ABC"}
Your syntax is right, but what you're asking for isn't what text fields are made for. A text field is tokenized (split into multiple tokens), and each token is searched by itself. So if the text inserted is "ABC DEF GHI", it will be split into three separate tokens, namely "ABC", "DEF" and "GHI". So when you're searching field:ABC, you're really asking for any document that has the token "ABC" somewhere.
Since you want to perform an exact match, you want to query against a field that is defined as a string field, as this will keep the value verbatim (including casing, so the matching will be case sensitive). You can tell Solr to index the same content into multiple fields by adding a copyFile instruction, telling it to take the content submitted for field foo and also copying it into field bar, allowing you to perform both an exact match if needed and a more general search if necessary.
If you need to perform exact, but case insensitive, searches, you can use a KeywordTokenizer - the KeywordTokenizer does nothing, keeping the whole string as a single token, before allowing you to add filters to the analysis chain. By adding a LowercaseFilter you tell Solr to lowercase the string as well before storing it (or querying for it).
You can use the "Analysis" page under the Solr admin page to experiment and see how content for your field is being processed for each step.
After that querying as string_field:ABC OR string_field:XYZ should do what you want (or string_field:(ABC OR XYZ) or a few other ways to express the same.
A wacky workaround I've just come up with:

Solr highlighting gives field/snippets with ANY term, instead of those that satisfy the query fully

I'm using Solr 5.x, standard highlighter, and i'm getting snippets which matches even one of the search terms only, even if i indicate q.op=AND.
I need ONLY the fields and snippets that matches ALL the terms (unless i say q.op=OR or just omit it), i.e. the field/snippet must satisfy the query. Solr does return the field/snippet that has all the terms, but also return many others.
I'm using hl.fl=*, to get the only fields having the terms, and searching against the default field ('text' containing full doc). Need to use * since i have multiple dynamic fields. Most fields are 'text_general' type (for search and HL), and some are 'string' type for faceting.
If its not possible for snippets to have all the terms, i MUST get only the fields that satisfy the query fully (since the question is more talking about matching all the terms, but the search query can become arbitrarily complex, so the fields/snippets should match the query).
Also, next is to get snippets highlighted with proximity based search/terms. What should i do/use for this? The fields coming in highlighting in this scenario should also satisfy the proximity query (unlike i get a field that contain any term, without regard to proximity constrains and other query terms etc)
Thanks for your help.
I've also encountered the same problem with highlighting. In my case, the query like
(foo AND bar) OR eggs
highlighted eggs and foo despite bar was not present in the document. I didn't manage to come up with proper solution, however I devised a dirty workaround.
I use the following query:
id:highlighted_document_id AND text:(my_original_query)
with debugQuery set to true. Then I parse explain text for highlighted_document_id. The text contains the terms from the query, which have contributed to the score. The terms, which should not be highlighted, are not present in the explanation.
The Python regex expressions I use to extract the terms (valid for Solr 5.2.1):
term_regex = re.compile(r'weight\(text:(.+) in')
wildcard_term_regex = re.compile(r'text:(.+), product')
then I simply search the markings in the highlighted text and remove them if the term doesn't match against any of the term in term_regex and wildcard_term_regex.
The solution is probably pretty limited, but works for me.

Lucene and Nickname matching

I have a series of docs containing a nickname ( even with spaces ) and an ID.
The nickname can be like ["example","nick n4me", "nosp4ces","A fancy guy"].
I have to find a query that allow me to find profiles by a perfect matching, a fuzzy, or event with partial character.
So if a write down "nick" or "nick name" or "nick name", the document "nickname" has always to come out.
I tried with something like:
nickname:(%1%^4 %1%~^3 %1%*^1)
where "%1%" is what I'm searching, but it doesn't work, especially for spaces or numbers nicknames. For example if i try to search "nick n" the query would be:
nickname:(nick n^4 nick n~^3 nick n*^1)
Boosting with ^ will only affect the scoring and not the matching, i.e. if your query does not match at all, boosting the terms or not won't make any difference.
In your specific example, the query won't match because:
1) nick n won't match because that would require that either the token nick or n have been tokenized;
2) EDIT: I found out that fuzzy queries work only on single terms, if you use the standard query parser. In your case, you should probably rewrite nick n~ using ComplexPhraseQueryParser, so you can do a fuzzy query on the whole PhraseQuery. Also, you can specify a threshold for your fuzzy query (technically, you are specifying a minimum Levenshtein distance). Obviously you have to adjust the threshold, and that usually requires some trial and error.
An easier tactic is to load all nicknames into one field -- in your example you would have 4 values for your nickname field. If you want embedded spaces in your nicknames, you will need to use a simpler analyzer than StandardAnalyzer or use phrase searches.

Solr Index appears to be valid - but returns no results

Solr newbie here.
I have created a Solr index and write a whole bunch of docs into it. I can see
from the Solr admin page that the docs exist and the schema is fine as well.
But when I perform a search using a test keyword I do not get any results back.
On entering * : *
into the query (in Solr admin page) I get all the results.
However, when I enter any other query (e.g. a term or phrase) I get no results.
I have verified that the field being queried is Indexed and contains the values I am searching for.
So I am confused what I am doing wrong.
Probably you don't have a <defaultSearchField> correctly set up. See this question.
Another possibility: your field is of type string instead of text. String fields, in contrast to text fields, are not analyzed, but stored and indexed verbatim.
I had the same issue with a new setup of Solr 8. The accepted answer is not valid anymore, because the <defaultSearchField> configuration will be deprecated.
As I found no answer to why Solr does not return results from any fields despite being indexed, I consulted the query documentation. What I found is the DisMax query parser:
The DisMax query parser is designed to process simple phrases (without complex syntax) entered by users and to search for individual terms across several fields using different weighting (boosts) based on the significance of each field. Additional options enable users to influence the score based on rules specific to each use case (independent of user input).
In contrast, the default Lucene parser only speaks about searching one field. So I gave DisMax a try and it worked very well!
Query example:
http://localhost:8983/solr/techproducts/select?defType=dismax&q=video
You can also specify which fields to search exactly to prevent unwanted side effects. Multiple fields are separated by spaces which translate to + in URLs:
http://localhost:8983/solr/techproducts/select?defType=dismax&q=video&qf=features+text
Last but not least, give the fields a weight:
http://localhost:8983/solr/techproducts/select?defType=dismax&q=video&qf=features^20.0+text^0.3
If you are using pysolr like I do, you can add those parameters to your search request like this:
results = solr.search('search term', **{
'defType': 'dismax',
'qf': 'features text'
})
In my case the problem was the format of the query. It seems that my setup, by default, was looking and an exact match to the entire value of the field. So, in order to get results if I was searching for the sit I had to query *sit*, i.e. use wildcards to get the expected result.
With solr 4, I had to solve this as per Mauricio's answer by defining type="text_en" to the field.
With solr 6, use text_general.

Solr query results using *

I want to provide for partial matching, so I am tacking on * to the end of search queries. What I've noticed is that a search query of gatorade will return 12 results whereas gatorade* returns 7. So * seems to be 1 or many as opposed to 0 or many ... how can I achieve this? Am I going about partial matching in Solr all wrong? Thanks.
First, I think Solr wildcards are better summarized by "0 or many" than "1 or many". I doubt that's the source of your problem. (For example, see the javadocs for WildcardQuery.)
Second, are you using stemming, because my first guess is that you're dealing with a stemming issue. Solr wildcards can behave kind of oddly with stemming. This is because wildcard expansion is based by searching through the list of terms stored in the inverted index; these terms are going to be in stemmed form (perhaps something like "gatorad"), rather than the words from the original source text (perhaps "gatorade" or "gatorades").
For example, suppose you have a stemmer that maps both "gatorade" and "gatorades" to the stem "gatorad". This means your inverted index will not contain either "gatorade" or "gatorades", only "gatorad". If you then issue the query gatorade*, Solr will walk the term index looking for all the stems beginning with "gatorade". But there are no such stems, so you won't get any matches. Similarly, if you searched gatorades*, Solr will look for all stems beginning with "gatorades". But there are no such stems, so you won't get any matches.
Third, for optimal help, I'd suggest posting some more information, in particular:
Some particular query URLs you are submitting to Solr
An excerpt from your schema.xml file. In particular, include A) the field elements for the fields you are having trouble with, and B) the field type definitions corresponding to those fields
so what I was looking for is to make the search term for 'gatorade' -> 'gatorade OR gatorade*' which will give me all the matches i'm looking for.
If you want a query to return all documents that match either a stemmed form of gatorade or words that begin with gatorade, you'll need to construct the query yourself: +(gatorade gatorade*). You could alternatively extend the SolrParser to do this, but that's more work.
Another alternative is to use NGrams and TokenFilterFactories, specifically the EdgeNGramFilterFactory. .
This will create indexes for ngrams or parts of words. Documents, with a min ngram size of 5 and max ngram size of 8, would index: Docum Docume Document Documents
There is a bit of a tradeoff for index size and time. One of the Solr books quotes as a rough guide: Indexing takes 10 times longer Uses 5 times more disk space Creates 6 times more distinct terms.
However, the EdgeNGram will do better than that.
You do need to make sure that you don't submit wildcard character in your queries. As you aren't doing a wildcard search, you are matching a search term on ngrams(parts of words).
My guess is the missing matches are "Gatorade" (with a capital 'G'), and you have a lowercase filter on your field. The idea is that you have filters in your schema.xml that preprocess the input data, but wildcard queries do not use them;
see this about how Solr deals with wildcard queries:
http://solr.pl/en/2010/12/20/wildcard-queries-and-how-solr-handles-them/
("Solr and wildcard handling").
From what I've read the wildcards only matched words with additional characters after the search term. "Gatorade*" would match Gatorades but not Gatorade itself. It appears there's been an update to Solr in version 3.6 that takes this into account by using the 'multiterm' field type instead of the 'text' field.
A better description is here:
http://bensch.be/the-solr-wildcard-problem-and-multiterm-solution

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