diff options
Diffstat (limited to 'lib/gitlab/background_migration/batching_strategies/primary_key_batching_strategy.rb')
-rw-r--r-- | lib/gitlab/background_migration/batching_strategies/primary_key_batching_strategy.rb | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/lib/gitlab/background_migration/batching_strategies/primary_key_batching_strategy.rb b/lib/gitlab/background_migration/batching_strategies/primary_key_batching_strategy.rb new file mode 100644 index 00000000000..80693728e86 --- /dev/null +++ b/lib/gitlab/background_migration/batching_strategies/primary_key_batching_strategy.rb @@ -0,0 +1,38 @@ +# frozen_string_literal: true + +module Gitlab + module BackgroundMigration + module BatchingStrategies + # Generic batching class for use with a BatchedBackgroundMigration. + # Batches over the given table and column combination, returning the MIN() and MAX() + # values for the next batch as an array. + # + # If no more batches exist in the table, returns nil. + class PrimaryKeyBatchingStrategy + 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 + def next_batch(table_name, column_name, batch_min_value:, batch_size:) + model_class = define_batchable_model(table_name) + + 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.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 |