The primary key value at which the BatchEnumerator
ends, inclusive of the value.
The relation from which the BatchEnumerator
yields batches.
The primary key value from which the BatchEnumerator
starts, inclusive of the value.
# File activerecord/lib/active_record/relation/batches/batch_enumerator.rb, line 25 def batch_size @of end
The size of the batches yielded by the BatchEnumerator
.
# File activerecord/lib/active_record/relation/batches/batch_enumerator.rb, line 63 def delete_all sum(&:delete_all) end
Deletes records in batches. Returns the total number of rows affected.
Person.in_batches.delete_all
See Relation#delete_all
for details of how each batch is deleted.
# File activerecord/lib/active_record/relation/batches/batch_enumerator.rb, line 83 def destroy_all each(&:destroy_all) end
Destroys records in batches.
Person.where("age < 10").in_batches.destroy_all
See Relation#destroy_all
for details of how each batch is destroyed.
# File activerecord/lib/active_record/relation/batches/batch_enumerator.rb, line 92 def each(&block) enum = @relation.to_enum(:in_batches, of: @of, start: @start, finish: @finish, load: false) return enum.each(&block) if block_given? enum end
Yields an ActiveRecord::Relation
object for each batch of records.
Person.in_batches.each do |relation| relation.update_all(awesome: true) end
# File activerecord/lib/active_record/relation/batches/batch_enumerator.rb, line 50 def each_record(&block) return to_enum(:each_record) unless block_given? @relation.to_enum(:in_batches, of: @of, start: @start, finish: @finish, load: true).each do |relation| relation.records.each(&block) end end
Looping through a collection of records from the database (using the all
method, for example) is very inefficient since it will try to instantiate all the objects at once.
In that case, batch processing methods allow you to work with the records in batches, thereby greatly reducing memory consumption.
Person.in_batches.each_record do |person| person.do_awesome_stuff end Person.where("age > 21").in_batches(of: 10).each_record do |person| person.party_all_night! end
If you do not provide a block to each_record
, it will return an Enumerator for chaining with other methods:
Person.in_batches.each_record.with_index do |person, index| person.award_trophy(index + 1) end
# File activerecord/lib/active_record/relation/batches/batch_enumerator.rb, line 72 def update_all(updates) sum do |relation| relation.update_all(updates) end end
Updates records in batches. Returns the total number of rows affected.
Person.in_batches.update_all("age = age + 1")
See Relation#update_all
for details of how each batch is updated.
© 2004–2021 David Heinemeier Hansson
Licensed under the MIT License.