Eclipse Community Forums: EclipseLink » Size of @OneToMany List

Help

Home

Home » Eclipse Projects » EclipseLink » Size of @OneToMany List(Reliable way to know size of @OneToMany List)

Show: Today's Messages :: Show Polls :: Message Navigator

Size of @OneToMany List [message #1815951]

Tue, 15 October 2019 19:36

JeeDev_User JeeDev_User

Messages: 1
Registered: October 2019

Junior Member

Hi all,
A classic example - I have Department entity, in which exist the following association:

//bi-directional many-to-one association to Employee
@OneToMany(mappedBy="department")
private List<Employee> employees;

Now, wondering, what is the reliable way to know , how many elements that list contains ? Is it enough to just call

employees.size();

OR i need to perform TypedQuery, ie,

select count(emp) from Employee emp where department =...

Report message to a moderator

Re: Size of @OneToMany List [message #1816396 is a reply to message #1815951]

Tue, 29 October 2019 01:50

Chris Delahunt

Messages: 1339
Registered: July 2009

Senior Member

Hopefully you just tried both.

If you do, you'll find that calling collection.size() is a java operation that runs on the collection. The collection is fetched only once from the Database, so if you plan to use the collection, that might be more efficient then calling a query for the count, and then having to access the collection to fetch it from the database.

Report message to a moderator

Previous Topic:	"Bug" with JPA InheritanceType SINGLE_TABLE and key
Next Topic:	No Snapshots for 2.6.6, 2.7.4 and2.7.5

Goto Forum:

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

]

Current Time: Wed Feb 26 01:39:09 GMT 2020

.:: Contact :: Home ::.

Breadcrumbs

Sign up to our Newsletter