diff options
Diffstat (limited to 'lib/gitlab/database/partitioning_migration_helpers/foreign_key_helpers.rb')
| -rw-r--r-- | lib/gitlab/database/partitioning_migration_helpers/foreign_key_helpers.rb | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/lib/gitlab/database/partitioning_migration_helpers/foreign_key_helpers.rb b/lib/gitlab/database/partitioning_migration_helpers/foreign_key_helpers.rb index 2def3a4d3a9..4402c42b136 100644 --- a/lib/gitlab/database/partitioning_migration_helpers/foreign_key_helpers.rb +++ b/lib/gitlab/database/partitioning_migration_helpers/foreign_key_helpers.rb @@ -6,6 +6,80 @@ module Gitlab module ForeignKeyHelpers include ::Gitlab::Database::SchemaHelpers + # Adds a foreign key with only minimal locking on the tables involved. + # + # In concept it works similarly to add_concurrent_foreign_key, but we have + # to add a special helper for partitioned tables for the following reasons: + # - add_concurrent_foreign_key sets the constraint to `NOT VALID` + # before validating it + # - Setting an FK to NOT VALID is not supported currently in Postgres (up to PG13) + # - Also, PostgreSQL will currently ignore NOT VALID constraints on partitions + # when adding a valid FK to the partitioned table, so they have to + # also be validated before we can add the final FK. + # Solution: + # - Add the foreign key first to each partition by using + # add_concurrent_foreign_key and validating it + # - Once all partitions have a foreign key, add it also to the partitioned + # table (there will be no need for a validation at that level) + # For those reasons, this method does not include an option to delay the + # validation, we have to force validate: true. + # + # source - The source (partitioned) table containing the foreign key. + # target - The target table the key points to. + # column - The name of the column to create the foreign key on. + # on_delete - The action to perform when associated data is removed, + # defaults to "CASCADE". + # name - The name of the foreign key. + # + def add_concurrent_partitioned_foreign_key(source, target, column:, on_delete: :cascade, name: nil) + partition_options = { + column: column, + on_delete: on_delete, + + # We'll use the same FK name for all partitions and match it to + # the name used for the partitioned table to follow the convention + # used by PostgreSQL when adding FKs to new partitions + name: name.presence || concurrent_partitioned_foreign_key_name(source, column), + + # Force the FK validation to true for partitions (and the partitioned table) + validate: true + } + + if foreign_key_exists?(source, target, **partition_options) + warning_message = "Foreign key not created because it exists already " \ + "(this may be due to an aborted migration or similar): " \ + "source: #{source}, target: #{target}, column: #{partition_options[:column]}, "\ + "name: #{partition_options[:name]}, on_delete: #{partition_options[:on_delete]}" + + Gitlab::AppLogger.warn warning_message + + return + end + + partitioned_table = find_partitioned_table(source) + + partitioned_table.postgres_partitions.order(:name).each do |partition| + add_concurrent_foreign_key(partition.identifier, target, **partition_options) + end + + with_lock_retries do + add_foreign_key(source, target, **partition_options) + end + end + + # Returns the name for a concurrent partitioned foreign key. + # + # Similar to concurrent_foreign_key_name (Gitlab::Database::MigrationHelpers) + # we just keep a separate method in case we want a different behavior + # for partitioned tables + # + def concurrent_partitioned_foreign_key_name(table, column, prefix: 'fk_rails_') + identifier = "#{table}_#{column}_fk" + hashed_identifier = Digest::SHA256.hexdigest(identifier).first(10) + + "#{prefix}#{hashed_identifier}" + end + # Creates a "foreign key" that references a partitioned table. Because foreign keys referencing partitioned # tables are not supported in PG11, this does not create a true database foreign key, but instead implements the # same functionality at the database level by using triggers. |