BatchSize (Hibernate Javadocs)

```
@Target({TYPE,METHOD,FIELD})
@Retention(RUNTIME)
public @interface BatchSize
```
Specifies a maximum batch size for batch fetching of the annotated entity or collection.
When batch fetching is enabled, Hibernate is able to fetch multiple instances of an entity or collection in a single round-trip to the database. Instead of a SQL select with just one primary key value in the where clause, the where clause contains a list of primary keys inside a SQL in condition. The primary key values to batch fetch are chosen from among the identifiers of unfetched entity proxies or collection roles associated with the session.
For example:
```
    @Entity
    @BatchSize(size = 100)
    class Product {
        ...
    }
 
```
will initialize up to 100 unfetched Product proxies in each trip to the database.
Similarly:
```
    @OneToMany
    @BatchSize(size = 5) /
    Set<Product> getProducts() { ... };
 
```
will initialize up to 5 unfetched collections of Products in each SQL select.
See Also:

FetchSettings.DEFAULT_BATCH_FETCH_SIZE

- Required Element Summary
  
  Required Elements
  Modifier and Type Required Element Description
  
  int size
  The maximum batch size, a strictly positive integer.

- Element Detail
  - size
```
int size
```
    The maximum batch size, a strictly positive integer.
    Default is defined by FetchSettings.DEFAULT_BATCH_FETCH_SIZE