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Diffstat (limited to 'lib/gitlab/background_migration/copy_column.rb')
-rw-r--r-- | lib/gitlab/background_migration/copy_column.rb | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/lib/gitlab/background_migration/copy_column.rb b/lib/gitlab/background_migration/copy_column.rb new file mode 100644 index 00000000000..a2cb215c230 --- /dev/null +++ b/lib/gitlab/background_migration/copy_column.rb @@ -0,0 +1,39 @@ +# frozen_string_literal: true + +module Gitlab + module BackgroundMigration + # CopyColumn is a simple (reusable) background migration that can be used to + # update the value of a column based on the value of another column in the + # same table. + # + # For this background migration to work the table that is migrated _has_ to + # have an `id` column as the primary key. + class CopyColumn + # table - The name of the table that contains the columns. + # copy_from - The column containing the data to copy. + # copy_to - The column to copy the data to. + # start_id - The start ID of the range of rows to update. + # end_id - The end ID of the range of rows to update. + def perform(table, copy_from, copy_to, start_id, end_id) + return unless connection.column_exists?(table, copy_to) + + quoted_table = connection.quote_table_name(table) + quoted_copy_from = connection.quote_column_name(copy_from) + quoted_copy_to = connection.quote_column_name(copy_to) + + # We're using raw SQL here since this job may be frequently executed. As + # a result dynamically defining models would lead to many unnecessary + # schema information queries. + connection.execute <<-SQL.strip_heredoc + UPDATE #{quoted_table} + SET #{quoted_copy_to} = #{quoted_copy_from} + WHERE id BETWEEN #{start_id} AND #{end_id} + SQL + end + + def connection + ActiveRecord::Base.connection + end + end + end +end |