If user searches for "John Banglore" or "Banglore John" then they should get John from Banglore at first position in result and then other related results.
how to do it ?
UserModel.js{ name:String, city:String }
and I have tried by splitting query string then converting to regex and then search but it is not returning John from Banglore at first position in result.
Backend - Node.js
Database - MongoDB
Module - mongoose
This could be solved with a simple approach for your specific use case
Where you split the name on the space character and do a set of regexes based on that.
Although that solves this case. You will likely run into other cases where the fuzzy matching capabilities are limited. It may be better to look into a Inverted Index such as elastic search for enhanced search capabilities.
Related
I am trying to configure Azure Search to find some strings that have special characters, for example
ABC*DEF
When I look for a the full term using "ABC*DEF", it works perfectly.
The problem comes if I want to use a regex term:
When I use a partial term, like /(.*)ABC(.*)/, the result has no problem
When I use a partial term, like /(.*)DEF(.*)/, the result has no problem
But when I try to look for something like /(.*)C\*D(.*)/, the result is empty.
I am using a standard analyzer. I tried also the keyword analyzer but that way the regex search doesn't work at all.
Any suggestions?
You won't be able to create a regex expression that matches ABC*DEF using the standard analyzer.
If you run "ABC\*DEF" through the analyzer api using "standard" analyzer, you will see that ABC*DEF gets divided into 2 tokens at indexing time -> "ABC" and "DEF". Regex expression are not analyzed, however, they need to match a token that exist in the index.
Since ABC\*DEF does not exist in the index (only "ABC" and "DEF" exist), you won't be able to find it using the expression you are searching for.
Using the "keyword" analyzer will keep the whole field as a single token, so if the field "only" contained the expression ABC\*DEF, then the regex expression would work on it, however, if ABC\*DEF is part of a larger paragraph of text, then that's probably not what you want to use.
Your best bet is to create a custom analyzer that tokenizes your text in the way that preserves the special characters that are relevant to your use case.
If you're searching for special chars, why don't you discard normal chars?
[^\w]
This question/answer dealt with a pretty similar topic, but I couldn't find the solution I was searching for.
How to practially use a keywordanalyzer in azure-search?
Starting situation:
I created a resource with multiple indexes. One of these indexes contains a Collection(Edm.String) field.
From this field i only want to get documents which exactly contain the search term. For example the field contains documents like these: "Hovercraft zero", "Hovercraft one", "Hovercraft two".
If the search term is "Hover" all three documents should be returned. If the search term is "craft zer" only the document "Hovercraft zero" should be returned. The document shouldn't get a higher score, the desired behaviour is that I only get the "Hovercraft zero" document as result.
Further information:
It is not possible to set the searchmode to all (like it was recommended in the question on the top) because I just want to set this behaviour for this specific field and not for all search queries. It also is not possible to let the responsibility on the user to enter the search term with quotes.
What I have tried so far:
Use the keyword analyzer like it was described in the question on
top: no success
Use an indexanalyzer with specific token filters (ngram,
lowercase) and a searchanalyzer as a keyword analyzer: no success
Use Charfilters to manipulate the search term and manually set the
quotes on the first and last position (craft zer -> "craft zer").
Like Yahnoosh explained in the question on top, the query parser
processes the query string before the analyzers are applied. So:
no success
Is there any solution for this issue?
Or is there a other approach to achieve the desired behaviour?
Hopefully someone can help.
Thanks in advance!
Using your example with three documents: "Hovercraft zero", "Hovercraft one", "Hovercraft two"
Issue a prefix query to find all documents that contain terms that start with "Hover"
search=Hover*
To match the term "craft zer", you need to use the keyword analyzer (or the keyword tokenizer with the lowercase token filter) at indexing time to make sure elements of your string collection are not tokenized. Then at query time you can issue a regex query (note regex queries are much slower than term or prefix queries)
search=/.craft zer./&queryType=full
Also, please use the Analyze API to test your custom analyzer configurations. It will help you make sure the analyzer produces the terms you expect.
Thanks #Yahnoosh for your answer, I found a solution that worked for me.
Short example:
I have an index including three fields (field1, field2, field3). From field3 I want a result where documents exactly contain the search term. From field1 and field2 I want do get a "standard" result.
Solution:
I manipulated the searchquery to ->
field1:{searchterm} || field2:{searchterm} || field3:"{searchterm}" &queryType=full
Using this searchquery field1 and field2 are queried in the "standard" way and field3 is queried with the behaviour i was searching for. Of course there are more efficient and elegant ways out there to solve this issue, but it worked for me.
If anybody has a better solution let me know ;)
I am working on a search feature in which I have to perform search operation in about 300,000 documents.
For this I have created a compound index over four fields and have given weight to them as well. By default if I search for a phrase having multiple words then mongoose searches for all the keywords with OR operation. Eg:- If you search for small cell lung then mongoose will search all document in which either one of these is available.
It is working very fast.
But my requirement is to perform AND operation. To achieve this I split all the words in a phrase and then put them in double quotes.So when user searches for a phrase having multiple words, search operation is performed as AND operation on each word. Eg:- If you search for small cell lung ("small" "cell" "lung") then it should find all those documents in which all are available. It is also working but it is very slow now.
Is there any way to make it faster.
I will share the code if required.
Thanks
Give a shot to this :
db.table.find("text", {search:"\"small\" \"cell\" \"lung\""})
Now above code will do the following :
If the search string includes phrases, the search performs an AND with
any other terms in the search string; e.g. search for "\"kiss me on
\" cheeks lips" searches for "Kiss Me on" and ("cheecks" or
"lips").
You can read it from here:
Docs
When you want to match the complete phrase, enclose the phrase in escaped double quotes:
db.table.find( { $text: { $search: "small cell lung" } } )
Also see the $text documentation on the mongodb site
CouchDB gives an opportunity to search values from startkey, for exact key-value pair etc
But is there any way to search for substring in specified field?
The problem is like this. Our news database consists of about 40,000 news documents. Say, they have title, content and url fields. We want to find news documents which have "restaurant" in their title. Is there any way to do it?
View Collation wiki page tells nothing :( And it seems strange to me that there's no tool to handle this problem and all I can to do is just parsing JSON results with Python, PHP or smth else. In MySQL it's simply LOCATE() function..
Use couchdb-lucene.
Be careful here. Lucene is not always the best answer.
If your only searching one limited field and only searching for a word like restaurant then lucene which is really meant to tokenize large texts/documents can be way overkill, you can get the same effect by splitting the title.
function(doc){
var stringarray = doc.title.split(" ");
for(var idx in stringarray)
emit(stringarray[idx],doc);
}
Also Lucene and Couchdb do not support substring search, where the string is not in the beginning of a word.
I use solr to search for documents and when trying to search for documents using this query "id:*", I get this query parser exception telling that it cannot parse the query with * or ? as the first character.
HTTP Status 400 - org.apache.lucene.queryParser.ParseException: Cannot parse 'id:*': '*' or '?' not allowed as first character in WildcardQuery
type Status report
message org.apache.lucene.queryParser.ParseException: Cannot parse 'id:*': '*' or '?' not allowed as first character in WildcardQuery
description The request sent by the client was syntactically incorrect (org.apache.lucene.queryParser.ParseException: Cannot parse 'id:*': '*' or '?' not allowed as first character in WildcardQuery).
Is there any patch for getting this to work with just * ? Or is it very costly to do such a query?
If you want all documents, do a query on *:*
If you want all documents with a certain field (e.g. id) try id:[* TO *]
Lucene doesn't allow you to start WildcardQueries with an asterisk by default, because those are incredibly expensive queries and will be very, very, very slow on large indexes.
If you're using the Lucene QueryParser, call setAllowLeadingWildcard(true) on it to enable it.
If you want all of the documents with a certain field set, you are much better off querying or walking the index programmatically than using QueryParser. You should really only use QueryParser to parse user input.
id:[a* TO z*] id:[0* TO 9*] etc.
I just did this in lukeall on my index and it worked, therefore it should work in Solr which uses the standard query parser. I don't actually use Solr.
In base Lucene there's a fine reason for why you'd never query for every document, it's because to query for a document you must use a new indexReader("DirectoryName") and apply a query to it. Therefore you could totally skip applying a query to it and use the indexReader methods numDocs() to get a count of all the documents, and document(int n) to retrieve any of the documents.
If you are just trying to get all documents, Solr does support the *:* query. It's the only time I know of that Solr will let you begin a query with an *. I'm sure you've probably seen this as the default query in the Solr admin page.
If you are trying to do a more specific query with an * as the first character, like say id:*456 then one of the best ways I've seen is to index that field twice. Once normally (field name: id), and once with all the characters reversed (field name: reverse_id). Then you could essentially do the query id:456 by sending the query reverse_id:654 instead. Hope that makes sense.
You can also search the Solr user group mailing list at http://www.mail-archive.com/solr-user#lucene.apache.org/ where questions like this come up quite often.
The following Solr issue is a request to be able to configure the default lucene query parser.
https://issues.apache.org/jira/browse/SOLR-218
In this issue you can find the following description how to 'patch' Solr. This modification would allow you to start queries with a *.
Jonas Salk: I've basically updated only one Java file: SolrQueryParser.java.
public SolrQueryParser(IndexSchema schema, String defaultField) {
...
setAllowLeadingWildcard(true);
setLowercaseExpandedTerms(true);
...
}
...
public SolrQueryParser(QParser parser, String defaultField, Analyzer analyzer) {
...
setAllowLeadingWildcard(true);
setLowercaseExpandedTerms(true);
...
}
I'm not sure if setLowercaseExpandedTerms is needed...
I'm assuming with id:* you're just trying to match all documents, right?
I've never used solr before, but in my Lucene experience, when ingesting data, we've added a hidden field to every document, then when we need to return every record we do a search for the string constant in that field that's the same for every record.
If you can't add a field like that in your situation, you could use a RegexQuery with a regex that would match anything that could be found in the id field.
Edit: actually answering the question. I've never heard of a patch to get that to work, but I would be surprised if it could even be made to work reasonably well. See this question for a reason why unconstrained PrefixQuery's can cause a problem.
Actually, I have been using a workaround for this. I append a character to the id, eg: A1, A2, etc.
With such values in the field, it is possible to search using the query id:A*
But would love to find whether a true solution exists.