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QueryDSL matching id using 'in' not working for huge list collection

Hi i am trying to fetch records based on a condition whether particular id is present in a custom provided list...the query works fine for alist of size 15K records....but when i pass list with larger size it fails... i know there is a limitation in postgresSQl when trying to use in clause...but i dont know how to overcome this ....any help is greatly appreciated..
public JPAQuery<Tuple> matchStudentResults(final List<String> studentNames, final List<String> studentCodes) {
JPAQuery<Tuple> tupleJPAQuery = queryFactory.select(name, code, id,effectiveDate,studentAddress,sharedCourses).from(qStudentProperty).distinct().where(
code.in(studentCodes).or(name.in(studentNames)).and(effectiveJoiningDate.eq(SimpleDateValidator.getDate(StudentConstants.EFFECTIVE_START_DATE))));
}
As shown above both the lists studentNames and studentCodes are custom lists with data coming from files and not from the DB....the above query works fine when the lists are having size less than 15K.But fails when the list size is greater...i am new to queryDSL and don't know how to overcome this scenerio..

Java EBean Play Framework. findOne() not working ? how to return one object instead of findList()?

//Below code is Not Working
//Here, my query just returns one object, So I am trying to use findOne() //method.
Query<Topic> query = Ebean.find(Topic.class);
Topic topic = new Topic();
Topic topic=Topic.find.where().eq("columnName", "nameToMatch").findOne();
//Below part is working if I use findList(). But I have to do get(0) to //fetch the topic which is not good practice I think.
List<Topic> topicList = Ebean.find(Topic.class).where().eq("columnName", "NametoMatch").findList();
topicList.get(0)
Can anyone provide ideas how to return just One Object instead of list ?

I don't know if findOne exists in Ebean, but when I need to retrieve only one object I use findUnique()

If you're sure the object you want to find is unique, you can get it via findUnique(): Topic.find.where().eq("columnName", "nameToMatch").findUnique();
Otherwise you can use findList() with setMaxRows(), because you don't want to load in memory whole result set:
Topic.find.where().eq("columnName", "nameToMatch").setMaxRows(1).findList();

Datastore query with IN operator

The new flexible environment datastore interface does not seem to support IN operation when running a query. I hope that I'm wrong, and if so, how can one use an IN operator in the new Java interface of Datastore?

A query like - WHERE color IN('RED', 'BLACK'), it is not supported by the Datastore (server side). Same is the case with OR operator (e.g. WHERE color='RED' OR color='BLACK'). Some client APIs have added this functionality by splitting the query into multiple and then merging the results from each query. The new google-cloud-java API does not support this yet. For now, you would have to run multiple queries for each value in the IN clause and merge the results.

Here’s an example from the documentation:
If you want to set more than one filter on a query, you must use CompositeFilter, which requires at least two filters.
Filter tooShortFilter = new FilterPredicate("height", FilterOperator.LESS_THAN, minHeight);
Filter tooTallFilter = new FilterPredicate("height", FilterOperator.GREATER_THAN, maxHeight);
Filter heightOutOfRangeFilter = CompositeFilterOperator.or(tooShortFilter, tooTallFilter);
Query q = new Query("Person").setFilter(heightOutOfRangeFilter);
You can also use .and(). The code here is for Java 7. For Java 8 you can find a corresponding code in the documentation referenced above. I hope that helps.
Now to IN. While I have not tried it myself recently, the current documentation states that it can still be used as an operator. According to it, something like the code below should work:
Filter propertyFilter = new FilterPredicate("height", FilterOperator.IN, minHeights);
Query q = new Query("Person").setFilter(propertyFilter);
Alternatively, you could use Google GQL. It will allow you to write SQL-like syntax, in which you can use in(...).

I tried using the repository query methods, but I got an error informing that it is not supported.
Only solved for me using the #Query annotation;
Example:
#Query("select * from UserGroup where name IN #names")
List<Company> findAllByName(List<String> names);

writing a basic n1ql query in java

I have just started learning Couchbase. I am trying to write a basic query using java sdk but I am not able to understand how to write it. Below is the query:
SELECT *
FROM users_with_orders usr
JOIN orders_with_users orders
ON KEYS ARRAY s.order_id FOR s IN usr.shipped_order_history END
This is for joining without array:
LetPath path = select("*,META(usr).id as _ID,META(usr).cas as _CAS).from(bucketName +" usr").join(bucketname +" orders").onKeys("usr.order_id)
How should I proceed with the above query for on keys array?
Thanks!!!!

As described in the docs on Querying from the SDK, you can use either a simple string with the Java SDK or use the DSL. For example:
// query with a simple string
System.out.println("Simple string query:");
N1qlQuery airlineQuery = N1qlQuery.simple("SELECT `travel-sample`.* FROM `travel-sample` WHERE name=\"United Airlines\" AND type=\"airline\"");
N1qlQueryResult queryResult = bucket.query(airlineQuery);
for (N1qlQueryRow result: queryResult) {
System.out.println(result.value());
}
//query with a parameter using the DSL
System.out.println("Parameterized query using the DSL:");
Statement statement = select(path(i("travel-sample"), "*")).from(i("travel-sample")).where(x("name").eq(x("$airline_param")).and(x("type").eq(s("airline"))));
JsonObject placeholderValues = JsonObject.create().put("airline_param", "United Airlines");
N1qlQuery airlineQueryParameterized = N1qlQuery.parameterized(statement, placeholderValues);
N1qlQueryResult queryResultParameterized = bucket.query(airlineQueryParameterized);
for (N1qlQueryRow row : queryResultParameterized) {
System.out.println(row);
}
(I posted a full gist of this example for the imports, etc.)
See the docs for more info, but you may want to use the DSL to allow IDE code completion and Java compile time checking. When developing an interactive web application, you'll probably also want to use parameterized statements (for security) and may even want prepared statements (for performance).

How do I query OrientDB Vertex graph object by Record ID in Java?

How do I retrieve an OrientDB Document/Object or Graph object using its Record ID? (Language: Java)
I'm referring to http://orientdb.com/docs/2.0/orientdb.wiki/Tutorial-Record-ID.html and Vertex.getId() / Edge.getId() methods.
It is just like an SQL query "SELECT * from aTable WHERE ID = 1".
Usage/purpose description: I want to store the generated ID after it is created by OrientDB, and later retrieve the same object using the same ID.

(1) I'd suggest using OrientDB 2.1, and its documentation, e.g. http://orientdb.com/docs/2.1/Tutorial-Record-ID.html
(2) From your post, it's unclear to me whether you need help obtaining the RID from the results of a query, or retrieving an object given its RID, so let me begin by mentioning that the former can be accomplished as illustrated by this example (in the case of an INSERT query):
ODocument result=db.command(new OCommandSQL(<INSERTQUERY>)).execute();
System.out.println(result.field("#rid"));
Going the other way around, there are several approaches. I have verified that the following does work using Version 2.1.8:
OrientGraph graph = new OrientGraph("plocal:PATH_TO_DB", "admin", "admin");
Vertex v = graph.getVertex("#16:0");
An alternative and more generic approach is to construct and execute a SELECT query of the form SELECT FROM :RID, along the lines of this example:
List<ODocument> results = db.query(new OSQLSynchQuery<ODocument>("select from " + rid));
for (ODocument aDoc : results) {
System.out.println(aDoc.field("name"));
}
(3) In practice, it will usually be better to use some other "handle" on OrientDB vertices and edges in Java code, or indeed when using any of the supported programming languages. For example, once one has a vertex as a Java Vertex, as in the "Vertex v" example above, one can usually use it.