(Quick Reference)
batchSize
Purpose
Customizes how many results are fetching during lazy loading.
Examples
class Book {
…
static mapping = {
batchSize 10
}
}Description
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
}
}
