81 lines
3.1 KiB
Ruby
81 lines
3.1 KiB
Ruby
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module ActiveRecord
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module Batches # :nodoc:
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def self.included(base)
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base.extend(ClassMethods)
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end
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# When processing large numbers of records, it's often a good idea to do
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# so in batches to prevent memory ballooning.
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module ClassMethods
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# Yields each record that was found by the find +options+. The find is
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# performed by find_in_batches with a batch size of 1000 (or as
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# specified by the <tt>:batch_size</tt> option).
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#
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# Example:
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#
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# Person.find_each(:conditions => "age > 21") do |person|
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# person.party_all_night!
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# end
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#
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# Note: This method is only intended to use for batch processing of
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# large amounts of records that wouldn't fit in memory all at once. If
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# you just need to loop over less than 1000 records, it's probably
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# better just to use the regular find methods.
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def find_each(options = {})
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find_in_batches(options) do |records|
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records.each { |record| yield record }
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end
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self
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end
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# Yields each batch of records that was found by the find +options+ as
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# an array. The size of each batch is set by the <tt>:batch_size</tt>
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# option; the default is 1000.
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#
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# You can control the starting point for the batch processing by
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# supplying the <tt>:start</tt> option. This is especially useful if you
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# want multiple workers dealing with the same processing queue. You can
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# make worker 1 handle all the records between id 0 and 10,000 and
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# worker 2 handle from 10,000 and beyond (by setting the <tt>:start</tt>
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# option on that worker).
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#
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# It's not possible to set the order. That is automatically set to
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# ascending on the primary key ("id ASC") to make the batch ordering
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# work. This also mean that this method only works with integer-based
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# primary keys. You can't set the limit either, that's used to control
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# the the batch sizes.
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#
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# Example:
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#
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# Person.find_in_batches(:conditions => "age > 21") do |group|
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# sleep(50) # Make sure it doesn't get too crowded in there!
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# group.each { |person| person.party_all_night! }
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# end
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def find_in_batches(options = {})
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raise "You can't specify an order, it's forced to be #{batch_order}" if options[:order]
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raise "You can't specify a limit, it's forced to be the batch_size" if options[:limit]
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start = options.delete(:start).to_i
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batch_size = options.delete(:batch_size) || 1000
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with_scope(:find => options.merge(:order => batch_order, :limit => batch_size)) do
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records = find(:all, :conditions => [ "#{table_name}.#{primary_key} >= ?", start ])
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while records.any?
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yield records
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break if records.size < batch_size
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records = find(:all, :conditions => [ "#{table_name}.#{primary_key} > ?", records.last.id ])
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end
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end
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end
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private
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def batch_order
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"#{table_name}.#{primary_key} ASC"
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end
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end
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end
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end
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