76 lines
3.2 KiB
Ruby
76 lines
3.2 KiB
Ruby
# frozen_string_literal: true
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module Gitlab
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module BackgroundMigration
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# Background migration that updates the value of one or more
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# columns using the value of other columns in the same table.
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#
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# - The {start_id, end_id} arguments are at the start so that it can be used
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# with `queue_batched_background_migration`
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# - Uses sub-batching so that we can keep each update's execution time at
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# low 100s ms, while being able to update more records per 2 minutes
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# that we allow background migration jobs to be scheduled one after the other
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# - We skip the NULL checks as they may result in not using an index scan
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# - The table that is migrated does _not_ need `id` as the primary key
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# We use the provided primary_key column to perform the update.
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class CopyColumnUsingBackgroundMigrationJob
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include Gitlab::Database::DynamicModelHelpers
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# start_id - The start ID of the range of rows to update.
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# end_id - The end ID of the range of rows to update.
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# batch_table - The name of the table that contains the columns.
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# batch_column - The name of the column we use to batch over the table.
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# sub_batch_size - We don't want updates to take more than ~100ms
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# This allows us to run multiple smaller batches during
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# the minimum 2.minute interval that we can schedule jobs
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# pause_ms - The number of milliseconds to sleep between each subbatch execution.
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# copy_from - List of columns containing the data to copy.
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# copy_to - List of columns to copy the data to. Order must match the order in `copy_from`.
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def perform(start_id, end_id, batch_table, batch_column, sub_batch_size, pause_ms, copy_from, copy_to)
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copy_from = Array.wrap(copy_from)
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copy_to = Array.wrap(copy_to)
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raise ArgumentError, 'number of source and destination columns must match' unless copy_from.count == copy_to.count
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assignment_clauses = column_assignment_clauses(copy_from, copy_to)
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parent_batch_relation = relation_scoped_to_range(batch_table, batch_column, start_id, end_id)
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parent_batch_relation.each_batch(column: batch_column, of: sub_batch_size) do |sub_batch|
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batch_metrics.time_operation(:update_all) do
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sub_batch.update_all(assignment_clauses)
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end
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pause_ms = 0 if pause_ms < 0
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sleep(pause_ms * 0.001)
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end
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end
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def batch_metrics
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@batch_metrics ||= Gitlab::Database::BackgroundMigration::BatchMetrics.new
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end
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private
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def connection
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ActiveRecord::Base.connection
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end
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def relation_scoped_to_range(source_table, source_key_column, start_id, stop_id)
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define_batchable_model(source_table).where(source_key_column => start_id..stop_id)
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end
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def column_assignment_clauses(copy_from, copy_to)
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assignments = copy_from.zip(copy_to).map do |from_column, to_column|
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from_column = connection.quote_column_name(from_column)
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to_column = connection.quote_column_name(to_column)
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"#{to_column} = #{from_column}"
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end
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assignments.join(', ')
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end
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end
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end
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end
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