37 lines
1.5 KiB
Ruby
37 lines
1.5 KiB
Ruby
# frozen_string_literal: true
|
|
|
|
module Gitlab
|
|
module BackgroundMigration
|
|
module BatchingStrategies
|
|
# This strategy provides an efficient way to iterate over columns with non-distinct values.
|
|
# A common use case would be iterating over a foreign key columns, for example issues.project_id
|
|
class LooseIndexScanBatchingStrategy < BaseStrategy
|
|
include Gitlab::Database::DynamicModelHelpers
|
|
|
|
# Finds and returns the next batch in the table.
|
|
#
|
|
# table_name - The table to batch over
|
|
# column_name - The column to batch over
|
|
# batch_min_value - The minimum value which the next batch will start at
|
|
# batch_size - The size of the next batch
|
|
# job_arguments - The migration job arguments
|
|
# job_class - The migration job class
|
|
def next_batch(table_name, column_name, batch_min_value:, batch_size:, job_arguments:, job_class: nil)
|
|
model_class = define_batchable_model(table_name, connection: connection)
|
|
|
|
quoted_column_name = model_class.connection.quote_column_name(column_name)
|
|
relation = model_class.where("#{quoted_column_name} >= ?", batch_min_value)
|
|
next_batch_bounds = nil
|
|
|
|
relation.distinct_each_batch(of: batch_size, column: column_name) do |batch| # rubocop:disable Lint/UnreachableLoop
|
|
next_batch_bounds = batch.pluck(Arel.sql("MIN(#{quoted_column_name}), MAX(#{quoted_column_name})")).first
|
|
|
|
break
|
|
end
|
|
|
|
next_batch_bounds
|
|
end
|
|
end
|
|
end
|
|
end
|
|
end
|