I'm using Neo4j 2 REST API and I have the ability to add plugins.
I have an entity in my database with the label 'Entity' and name 'United Kingdom'.
How do I execute a fuzzy search to find this entity.
I would like to be able to find it using queries like
United
Kingdom
Uniter Kingdom
United Kinjdom
So the .*<query>.* won't do it.
I notice there was support for something like this in previous versions.
start n = node:index("name : 'United Kinjom'~0.2") return n
But this doesn't appear to work anymore.
It still works. Adding fulltext search to the automatic new schema indexes is on the roadmap. Until then you can still use the "legacy" indexes.
http://jexp.de/blog/2014/03/full-text-indexing-fts-in-neo4j-2-0/
Related
I'm new to SQL and I'm currently thinking about an effective way to build out my database. It's a language learning application and I'm torn between two approaches:
Keeping all of my words, regardless of their language, in one giant words table
Splitting my words into separate tables based on their language, ie: words_french, words_italian, etc.
In the second scenario, are there approaches that I can use (perhaps within Postgres) that would allow me target the words_french table in the event that I'm currently working through french lessons / content and need to lookup associated french words?
I feel like there would be some sort of concat process like so: words_${language} and as of this moment I'd figure i'd have to resolve this within JS or something else on the frontend.
-- also, is breaking words and other content into their respective table_language even a valid approach?
Any ideas?
Use Option 1. Option 2 would be horribly difficult to work with.
Word table:
WordId
Word
Language
1
a
English
2
un
French
As Dimitar Spasovski suggests, if you have a need for additional attributes associated with the language, you should also have a Language table. Then replace the Language column in the Word with LanguageId to make the relationship.
Watching or reading some data modeling or data architecture classes online will help.
I am working on neo4j database version 2.0.I have following requirements :
Case 1. I want to fetch all records where name contains some string,for example if i am searching for Neo4j then all records having name Neo4j Data,Neo4j Database,Neo4jDatabase etc. should be returned.
Case 2. When i want to fire field less query,if a set of properties is having matching value then those records should be returned or it may also be global level instead of label level.
Case Sensitivity is also a point.
I have read multiple thing about like,index,full text search,legacy index etc.,so what will be the best fit for my case,or i have to use elastic search etc.
I am using spring-data-neo4j in my application,so provide some configuration for SDN
Annotate your name with #Indexed annotation:
#Indexed(indexName = "whateverIndexName", indexType = IndexType.FULLTEXT)
private String name;
Then query for it following way (example for method in SDN repository, you can use similar anywhere else you use cypher):
#Query("START n=node:whateverIndexName({query}) return n"
Set<Topic> findByName(#Param("query") String query);
Neo4j uses lucene as backend for indexing so the query value must be a valid lucene query, e.g. "name:neo4j" or "name:neo4j*".
There is an article that explains the confusion around various Neo4j indexes http://nigelsmall.com/neo4j/index-confusion.
I don't think you need to be using elastic search-- you can use the legacy indexes or the lucene indexes to do full text searches.
Check out Michael Hunger's blog: jexp.de/blog
thix post specifically: http://jexp.de/blog/2014/03/full-text-indexing-fts-in-neo4j-2-0/
I am having only "Europe" being indexed along with some related data,but when someone searches using the word "Germany" although there is nothing specifically indexed for Germany but logically I can provide results under Europe than providing nothing at all,is there any way to do this? Does lunene have any supporting libraries which can do this?
But I dont want to have any geo-sptial search so how can we achieve this
I think that would just work out of the box by using a multi-valued field. You can have an indexed field which contains geo information (let's call it "place") such as Munich, Bavaria, Germany, Europe, World or Nice, French Riviera, France, Europe, World. Then, if you are looking for something in Bavaria, just run the query:
+text:something +place:(Bavaria Germany Europe World)
This will make all documents which have "something" in their text field appear in the result set, and boost documents depending on how far they are from Bavaria.
I like to use Hibernate Search for implementing an sophisticated autosuggestion feature across multiple input fields on a web page.
Each input field is for its own entity, let's say Country and City. There is a many-to-one relationship between both entities
(countries contain cities).
The autosuggestion should work such that when typing e.g. a country name prefix and the city field is already filled,
you get only suggestions for countries that have such a city (and vice versa).
The server side autosuggestion service should return list of projections
(entityId, entityName) which are rendered into the input field (dropdown, whatever).
According to the schema and after having read the manual I tried the following index schema:
SearchMapping mapping = new SearchMapping();
mapping.analyzerDef(...
.entity(City.class).indexed().indexName("MyIndex")
.property("cityId", ElementType.FIELD)
.documentId()
.name("id")
.property("name", ElementType.FIELD)
.documentId()
.name("id")
.property("country", ElementType.METHOD)
.indexEmbedded()
.entity(Country.class).indexed()
.property("id", ElementType.FIELD)
.documentId()
.name("id")
.property("name", ElementType.METHOD)
.field()
.name("name")
This mapping defines City to be the main entity, right?
I have indexed all cities and am able to query for them (also by combining both fields). However, I only get matches when querying for cities.
i.e. when querying like
fullTextSession.getSearchFactory().buildQueryBuilder().forEntity(City.class).get();
This is not useful for the country field becuse when I type in "Spain", I get a single row for each city of Spain. (Spain, Spain, Spain, Spain ,.... ;-))
The question is: How is it possible to search for country entities? Changing the index structure? The indexing procedure? Or how to query?
The only way I found was to setup a Facet for country, and you the different possible facets as autosuggestion. However, this is also not perfect
since it is not possible to sort facets alphabetically.
Of course, in this example, I could switch both entities in the mapping, but suppose scenarios with more complex entity graphs.
UPDATE: adding queries requested in comment
For building queries, I employ the QueryBuilder. The following produces a result set like in the Spain example:
fullTextSession.getSearchFactory().buildQueryBuilder().forEntity(City.class).get();
with query:
country.name:Spain
If I try to use a query builder for countries
fullTextSession.getSearchFactory().buildQueryBuilder().forEntity(Country.class).get();
and query:
name:Spain
I get no results.
You are not showing your actual query. You don't have to use the query DSL, but you can also write native Lucene queries. In both cases (DSL or native Lucene) you can combine queries via boolean logic. Embedded entities follow the java bean notation. The country name would for example in a city query be reached as country.name. Again, without your actual query it is hard to give any more specific feedback.
Last, but not least, facets can also be sorted alphabetically. Check FacetSortOrder.COUNT_DESC.
I'm using Hibernate for ORM of my Java app to an Oracle database (not that the database vendor matters, we may switch to another database one day), and I want to retrieve objects from the database according to user-provided strings. For example, when searching for people, if the user is looking for people who live in 'fran', I want to be able to give her people in San Francisco.
SQL is not my strong suit, and I prefer Hibernate's Criteria building code to hard-coded strings as it is. Can anyone point me in the right direction about how to do this in code, and if impossible, how the hard-coded SQL should look like?
Thanks,
Yuval =8-)
For the simple case you describe, look at Restrictions.ilike(), which does a case-insensitive search.
Criteria crit = session.createCriteria(Person.class);
crit.add(Restrictions.ilike('town', '%fran%');
List results = crit.list();
Criteria crit = session.createCriteria(Person.class);
crit.add(Restrictions.ilike('town', 'fran', MatchMode.ANYWHERE);
List results = crit.list();
If you use Spring's HibernateTemplate to interact with Hibernate, here is how you would do a case insensitive search on a user's email address:
getHibernateTemplate().find("from User where upper(email)=?", emailAddr.toUpperCase());
You also do not have to put in the '%' wildcards. You can pass MatchMode (docs for previous releases here) in to tell the search how to behave. START, ANYWHERE, EXACT, and END matches are the options.
The usual approach to ignoring case is to convert both the database values and the input value to upper or lower case - the resultant sql would have something like
select f.name from f where TO_UPPER(f.name) like '%FRAN%'
In hibernate criteria restrictions.like(...).ignoreCase()
I'm more familiar with Nhibernate so the syntax might not be 100% accurate
for some more info see pro hibernate 3 extract and hibernate docs 15.2. Narrowing the result set
This can also be done using the criterion Example, in the org.hibernate.criterion package.
public List findLike(Object entity, MatchMode matchMode) {
Example example = Example.create(entity);
example.enableLike(matchMode);
example.ignoreCase();
return getSession().createCriteria(entity.getClass()).add(
example).list();
}
Just another way that I find useful to accomplish the above.
Since Hibernate 5.2 session.createCriteria is deprecated. Below is solution using JPA 2 CriteriaBuilder. It uses like and upper:
CriteriaBuilder builder = session.getCriteriaBuilder();
CriteriaQuery<Person> criteria = builder.createQuery(Person.class);
Root<Person> root = criteria.from(Person.class);
Expression<String> upper = builder.upper(root.get("town"));
criteria.where(builder.like(upper, "%FRAN%"));
session.createQuery(criteria.select(root)).getResultList();
Most default database collations are not case-sensitive, but in the SQL Server world it can be set at the instance, the database, and the column level.
You could look at using Compass a wrapper above lucene.
http://www.compass-project.org/
By adding a few annotations to your domain objects you get achieve this kind of thing.
Compass provides a simple API for working with Lucene. If you know how to use an ORM, then you will feel right at home with Compass with simple operations for save, and delete & query.
From the site itself.
"Building on top of Lucene, Compass simplifies common usage patterns of Lucene such as google-style search, index updates as well as more advanced concepts such as caching and index sharding (sub indexes). Compass also uses built in optimizations for concurrent commits and merges."
I have used this in the past and I find it great.