Customizes how many results are fetching during lazy loading.

```
class Book {
…
static mapping = {
batchSize 10
}
}
```

Usage: `batchSize(integer)`

Given a lazy association where an `Author`

has many `Books`

, GORM will perform one query to get a hold of the `Author`

and then an additional query for each associated `Book`

. This is what is known as the N+1 problem and can often be worked around by using a join query. However, joins can be expensive.

Batch fetching is an optimization of lazy loading so that if, for example, you set a `batchSize`

of 10 and you have an `Author`

that has written 30 books, instead of 31 queries you get 4 (1 to fetch the `Author`

and then three batches of 10):

```
static mapping = {
batchSize 10
}
```

You can also configure `batchSize`

on a per association basis:

class Author { static hasMany = [books:Book] static mapping = { books batchSize: 10 } }