Lazy Loading / Eager fetching in Hibernate

Question

I have set the property lazy="false" in my hbm file for the column Contact in the table "Employee"

The below query is executed to retrieve the Employee with Id 5:

Select e from Employee e where e.id = 5

On execution, a number of queries are being executed and I guess it is due to non Lazy Loading.

How to make sure that only one query is executed? Can we change the query keeping the property lazy as false? If not, what should be the change in the query to retrieve the record?

I'm using Spring+Hibernate

Jay Otterbein · Accepted Answer · 2012-03-08 16:27:44Z

2

Based on your query, I'm going to assume you're using HQL for this. I'm also going to assume Contact is a reference.

select e from Employee e left join fetch e.Contact where e.Id = 5

answered Mar 8, 2012 at 16:27

Jay Otterbein

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12 Comments

Chillax Over a year ago

Thanks. Yes im using HQL and Contact is a reference. Here we should set lazy="true" yea?

Jay Otterbein Over a year ago

Setting lazy to true or false won't change this query getting the Contact automatically. You'll have to decide based on your requirements and performance if you want Contact to be default lazy and only eagerly load in this query or not.

Chillax Over a year ago

so that means if I set lazy="false" and execute the above query, Contact will not be loaded? I thought setting lazy="false" will load the Contact always?

Jay Otterbein Over a year ago

Maybe I didn't understand the original point. I thought you were looking for a way to keep Contact lazy but load it eagerly sometimes. Executing the above query will load Contact every time regardless of the lazy loading setting. Are you looking for something else?

Jay Otterbein Over a year ago

Yea, it will change getting the employee from 2 queries to 1 query. This query does the same as setting the Contact to eagerly loading with join fetch. If you have multiple collection references you'll have to look out for cross joins, more info on that here

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