Class: Gitlab::BackgroundMigration::CopyColumnUsingBackgroundMigrationJob

Inherits:
BatchedMigrationJob
  • Object
show all
Defined in:
lib/gitlab/background_migration/copy_column_using_background_migration_job.rb

Overview

Background migration that updates the value of one or more columns using the value of other columns in the same table.

  • The end_id arguments are at the start so that it can be used with ‘queue_batched_background_migration`

  • Uses sub-batching so that we can keep each update’s execution time at low 100s ms, while being able to update more records per 2 minutes that we allow background migration jobs to be scheduled one after the other

  • We skip the NULL checks as they may result in not using an index scan

  • The table that is migrated does not need ‘id` as the primary key We use the provided primary_key column to perform the update.

Constant Summary

Constants inherited from BatchedMigrationJob

BatchedMigrationJob::DEFAULT_FEATURE_CATEGORY

Constants included from Database::DynamicModelHelpers

Database::DynamicModelHelpers::BATCH_SIZE

Instance Method Summary collapse

Methods inherited from BatchedMigrationJob

#batch_metrics, feature_category, #filter_batch, generic_instance, #initialize, job_arguments, job_arguments_count, operation_name, scope_to

Methods included from Database::DynamicModelHelpers

#define_batchable_model, #each_batch, #each_batch_range

Constructor Details

This class inherits a constructor from Gitlab::BackgroundMigration::BatchedMigrationJob

Instance Method Details

#perform ⇒ Object 



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# File 'lib/gitlab/background_migration/copy_column_using_background_migration_job.rb', line 21

def perform
  assignment_clauses = build_assignment_clauses(copy_from, copy_to)

  each_sub_batch do |relation|
    relation.update_all(assignment_clauses)
  end
end