Module: Gitlab::Database::MigrationHelpers

Includes:
AsyncConstraints::MigrationHelpers, AsyncIndexes::MigrationHelpers, DynamicModelHelpers, WraparoundVacuumHelpers, Gitlab::Database::Migrations::BackgroundMigrationHelpers, Gitlab::Database::Migrations::BatchedBackgroundMigrationHelpers, Gitlab::Database::Migrations::ConstraintsHelpers, Gitlab::Database::Migrations::ExtensionHelpers, Gitlab::Database::Migrations::LockRetriesHelpers, Gitlab::Database::Migrations::RedisHelpers, Gitlab::Database::Migrations::ReestablishedConnectionStack, Gitlab::Database::Migrations::SidekiqHelpers, Gitlab::Database::Migrations::TimeoutHelpers, RenameTableHelpers
Included in:
BackgroundMigration::LegacyUploadsMigrator, CascadingNamespaceSettings, V2, PartitioningMigrationHelpers::IndexHelpers, PartitioningMigrationHelpers::TableManagementHelpers
Defined in:
lib/gitlab/database/migration_helpers.rb,
lib/gitlab/database/migration_helpers/v2.rb,
lib/gitlab/database/migration_helpers/announce_database.rb,
lib/gitlab/database/migration_helpers/convert_to_bigint.rb,
lib/gitlab/database/migration_helpers/wraparound_autovacuum.rb,
lib/gitlab/database/migration_helpers/restrict_gitlab_schema.rb,
lib/gitlab/database/migration_helpers/loose_foreign_key_helpers.rb,
lib/gitlab/database/migration_helpers/wraparound_vacuum_helpers.rb,
lib/gitlab/database/migration_helpers/cascading_namespace_settings.rb,
lib/gitlab/database/migration_helpers/automatic_lock_writes_on_tables.rb

Defined Under Namespace

Modules: AnnounceDatabase, AutomaticLockWritesOnTables, CascadingNamespaceSettings, ConvertToBigint, LooseForeignKeyHelpers, RestrictGitlabSchema, V2, WraparoundAutovacuum, WraparoundVacuumHelpers

Constant Summary collapse

DEFAULT_TIMESTAMP_COLUMNS = 
%i[created_at updated_at].freeze

Constants included from DynamicModelHelpers

DynamicModelHelpers::BATCH_SIZE

Constants included from Gitlab::Database::Migrations::RedisHelpers

Gitlab::Database::Migrations::RedisHelpers::SCAN_START_CURSOR

Constants included from Gitlab::Database::Migrations::SidekiqHelpers

Gitlab::Database::Migrations::SidekiqHelpers::DEFAULT_MAX_ATTEMPTS, Gitlab::Database::Migrations::SidekiqHelpers::DEFAULT_TIMES_IN_A_ROW

Constants included from Gitlab::Database::Migrations::ConstraintsHelpers

Gitlab::Database::Migrations::ConstraintsHelpers::MAX_IDENTIFIER_NAME_LENGTH

Constants included from Gitlab::Database::Migrations::BatchedBackgroundMigrationHelpers

Gitlab::Database::Migrations::BatchedBackgroundMigrationHelpers::BATCH_CLASS_NAME, Gitlab::Database::Migrations::BatchedBackgroundMigrationHelpers::BATCH_MIN_DELAY, Gitlab::Database::Migrations::BatchedBackgroundMigrationHelpers::BATCH_MIN_VALUE, Gitlab::Database::Migrations::BatchedBackgroundMigrationHelpers::BATCH_SIZE, Gitlab::Database::Migrations::BatchedBackgroundMigrationHelpers::NonExistentMigrationError, Gitlab::Database::Migrations::BatchedBackgroundMigrationHelpers::SUB_BATCH_SIZE

Constants included from Gitlab::Database::Migrations::BackgroundMigrationHelpers

Gitlab::Database::Migrations::BackgroundMigrationHelpers::BATCH_SIZE, Gitlab::Database::Migrations::BackgroundMigrationHelpers::JOB_BUFFER_SIZE

Instance Method Summary collapse

Methods included from WraparoundVacuumHelpers

#check_if_wraparound_in_progress

Methods included from AsyncConstraints::MigrationHelpers

#prepare_async_check_constraint_validation, #prepare_async_foreign_key_validation, #prepare_partitioned_async_foreign_key_validation, #unprepare_async_check_constraint_validation, #unprepare_async_foreign_key_validation, #unprepare_partitioned_async_foreign_key_validation

Methods included from AsyncIndexes::MigrationHelpers

#async_index_creation_available?, #prepare_async_index, #prepare_async_index_from_sql, #prepare_async_index_removal, #unprepare_async_index, #unprepare_async_index_by_name

Methods included from RenameTableHelpers

#finalize_table_rename, #rename_table_safely, #undo_finalize_table_rename, #undo_rename_table_safely

Methods included from Gitlab::Database::Migrations::RedisHelpers

#queue_redis_migration_job

Methods included from Gitlab::Database::Migrations::SidekiqHelpers

#sidekiq_queue_length, #sidekiq_queue_migrate, #sidekiq_remove_jobs

Methods included from Gitlab::Database::Migrations::ExtensionHelpers

#create_extension, #drop_extension

Methods included from Gitlab::Database::Migrations::ConstraintsHelpers

#add_check_constraint, #add_not_null_constraint, #add_text_limit, #check_constraint_exists?, check_constraint_exists?, #check_constraint_name, #check_not_null_constraint_exists?, #check_text_limit_exists?, #copy_check_constraints, #drop_constraint, #remove_check_constraint, #remove_not_null_constraint, #remove_text_limit, #rename_constraint, #switch_constraint_names, #text_limit_name, #validate_check_constraint, #validate_not_null_constraint, #validate_text_limit

Methods included from Gitlab::Database::Migrations::TimeoutHelpers

#disable_statement_timeout

Methods included from Gitlab::Database::Migrations::LockRetriesHelpers

#with_lock_retries

Methods included from Gitlab::Database::Migrations::BatchedBackgroundMigrationHelpers

#delete_batched_background_migration, #ensure_batched_background_migration_is_finished, #finalize_batched_background_migration, #gitlab_schema_from_context, #queue_batched_background_migration

Methods included from Gitlab::Database::Migrations::BackgroundMigrationHelpers

#delete_job_tracking, #delete_queued_jobs, #finalize_background_migration, #migrate_in, #queue_background_migration_jobs_by_range_at_intervals, #requeue_background_migration_jobs_by_range_at_intervals

Methods included from Gitlab::Database::Migrations::ReestablishedConnectionStack

#with_restored_connection_stack

Instance Method Details

#add_concurrent_foreign_key(source, target, column:, **options) ⇒ Object

Adds a foreign key with only minimal locking on the tables involved.

This method only requires minimal locking

source - The source 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. target_column - The name of the referenced column, defaults to “id”. on_delete - The action to perform when associated data is removed,

defaults to "CASCADE".

on_update - The action to perform when associated data is updated,

defaults to nil. This is useful for multi column FKs if
it's desirable to update one of the columns.

name - The name of the foreign key. validate - Flag that controls whether the new foreign key will be validated after creation.

If the flag is not set, the constraint will only be enforced for new data.

reverse_lock_order - Flag that controls whether we should attempt to acquire locks in the reverse

order of the ALTER TABLE. This can be useful in situations where the foreign
key creation could deadlock with another process.



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# File 'lib/gitlab/database/migration_helpers.rb', line 240

def add_concurrent_foreign_key(source, target, column:, **options)
  options.reverse_merge!({
    on_delete: :cascade,
    on_update: nil,
    target_column: :id,
    validate: true,
    reverse_lock_order: false,
    allow_partitioned: false,
    column: column
  })

  # Transactions would result in ALTER TABLE locks being held for the
  # duration of the transaction, defeating the purpose of this method.
  if transaction_open?
    raise 'add_concurrent_foreign_key can not be run inside a transaction'
  end

  if !options.delete(:allow_partitioned) && table_partitioned?(source)
    raise ArgumentError, 'add_concurrent_foreign_key can not be used on a partitioned ' \
      'table. Please use add_concurrent_partitioned_foreign_key on the partitioned table ' \
      'as we need to create foreign keys on each partition and a FK on the parent table'
  end

  options[:name] ||= concurrent_foreign_key_name(source, column)
  options[:primary_key] = options[:target_column]
  check_options = options.slice(:column, :on_delete, :on_update, :name, :primary_key)

  if foreign_key_exists?(source, target, **check_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: #{options[:column]}, "\
      "name: #{options[:name]}, on_update: #{options[:on_update]}, "\
      "on_delete: #{options[:on_delete]}"

    Gitlab::AppLogger.warn warning_message
  else
    execute_add_concurrent_foreign_key(source, target, options)
  end

  # Validate the existing constraint. This can potentially take a very
  # long time to complete, but fortunately does not lock the source table
  # while running.
  # Disable this check by passing `validate: false` to the method call
  # The check will be enforced for new data (inserts) coming in,
  # but validating existing data is delayed.
  #
  # Note this is a no-op in case the constraint is VALID already

  if options[:validate]
    disable_statement_timeout do
      execute("ALTER TABLE #{source} VALIDATE CONSTRAINT #{options[:name]};")
    end
  end
end

#add_concurrent_index(table_name, column_name, options = {}) ⇒ Object

Creates a new index, concurrently

Example:

add_concurrent_index :users, :some_column

See Rails’ ‘add_index` for more info on the available arguments.



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# File 'lib/gitlab/database/migration_helpers.rb', line 91

def add_concurrent_index(table_name, column_name, options = {})
  if transaction_open?
    raise 'add_concurrent_index can not be run inside a transaction, ' \
      'you can disable transactions by calling disable_ddl_transaction! ' \
      'in the body of your migration class'
  end

  if !options.delete(:allow_partition) && partition?(table_name)
    raise ArgumentError, 'add_concurrent_index can not be used on a partitioned '  \
      'table. Please use add_concurrent_partitioned_index on the partitioned table ' \
      'as we need to create indexes on each partition and an index on the parent table'
  end

  options = options.merge({ algorithm: :concurrently })

  if index_exists?(table_name, column_name, **options)
    name = options[:name] || index_name(table_name, column_name)
    _, schema = table_name.to_s.split('.').reverse

    if index_invalid?(name, schema: schema)
      say "Index being recreated because the existing version was INVALID: table_name: #{table_name}, column_name: #{column_name}"

      remove_concurrent_index_by_name(table_name, name)
    else
      say "Index not created because it already exists (this may be due to an aborted migration or similar): table_name: #{table_name}, column_name: #{column_name}"

      return
    end
  end

  disable_statement_timeout do
    add_index(table_name, column_name, **options)
  end

  # We created this index. Now let's remove the queuing entry for async creation in case it's still there.
  unprepare_async_index(table_name, column_name, **options)
end

#add_primary_key_using_index(table_name, pk_name, index_to_use) ⇒ Object 



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# File 'lib/gitlab/database/migration_helpers.rb', line 1071

def add_primary_key_using_index(table_name, pk_name, index_to_use)
  execute <<~SQL
    ALTER TABLE #{quote_table_name(table_name)} ADD CONSTRAINT #{quote_table_name(pk_name)} PRIMARY KEY USING INDEX #{quote_table_name(index_to_use)}
  SQL
end

#add_sequence(table_name, column_name, sequence_name, start_value) ⇒ Object 



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# File 'lib/gitlab/database/migration_helpers.rb', line 1092

def add_sequence(table_name, column_name, sequence_name, start_value)
  execute <<~SQL
    CREATE SEQUENCE #{quote_table_name(sequence_name)} START #{start_value};
    ALTER TABLE #{quote_table_name(table_name)} ALTER COLUMN #{quote_column_name(column_name)} SET DEFAULT nextval(#{quote(sequence_name)})
  SQL
end

#add_timestamps_with_timezone(table_name, options = {}) ⇒ Object

Adds ‘created_at` and `updated_at` columns with timezone information.

This method is an improved version of Rails’ built-in method ‘add_timestamps`.

By default, adds ‘created_at` and `updated_at` columns, but these can be specified as:

add_timestamps_with_timezone(:my_table, columns: [:created_at, :deleted_at])

This allows you to create just the timestamps you need, saving space.

Available options are:

:default - The default value for the column.
:null - When set to `true` the column will allow NULL values.
      The default is to not allow NULL values.
:columns - the column names to create. Must end with `_at`.
           Default value: `DEFAULT_TIMESTAMP_COLUMNS`

All options are optional.



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# File 'lib/gitlab/database/migration_helpers.rb', line 53

def add_timestamps_with_timezone(table_name, options = {})
  columns = options.fetch(:columns, DEFAULT_TIMESTAMP_COLUMNS)

  columns.each do |column_name|
    validate_timestamp_column_name!(column_name)

    add_column(
      table_name,
      column_name,
      :datetime_with_timezone,
      default: options[:default],
      null: options[:null] || false
    )
  end
end

#backfill_conversion_of_integer_to_bigint(table, columns, primary_key: :id, batch_size: 20_000, sub_batch_size: 1000, interval: 2.minutes) ⇒ Object

Backfills the new columns used in an integer-to-bigint conversion using background migrations.

  • This helper should be called from a post-deployment migration.

  • In order for this helper to work properly, the new columns must be first initialized with the ‘initialize_conversion_of_integer_to_bigint` helper.

  • It tracks the scheduled background jobs through Gitlab::Database::BackgroundMigration::BatchedMigration, which allows a more thorough check that all jobs succeeded in the cleanup migration and is way faster for very large tables.

    Note: this helper is intended to be used in a post-deployment migration, to ensure any new code is deployed (including background job changes) before we begin processing the background migration.

    This helper is part 2 of a multi-step migration process:

    1. initialize_conversion_of_integer_to_bigint to create the new columns and database trigger

    2. backfill_conversion_of_integer_to_bigint to copy historic data using background migrations

    3. remaining steps TBD, see #288005

table - The name of the database table containing the column columns - The name, or an array of names, of the column(s) we want to convert to bigint. primary_key - The name of the primary key column (most often :id) batch_size - The number of rows to schedule in a single background migration sub_batch_size - The smaller batches that will be used by each scheduled job

to update the table. Useful to keep each update at ~100ms while executing
more updates per interval (2.minutes)
Note that each execution of a sub-batch adds a constant 100ms sleep
 time in between the updates, which must be taken into account
 while calculating the batch, sub_batch and interval values.

interval - The time interval between every background migration

example: Assume that we have figured out that updating 200 records of the events

table takes ~100ms on average.

We can set the sub_batch_size to 200, leave the interval to the default

and set the batch_size to 50_000 which will require
~50s = (50000 / 200) * (0.1 + 0.1) to complete and leaves breathing space
between the scheduled jobs



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# File 'lib/gitlab/database/migration_helpers.rb', line 818

def backfill_conversion_of_integer_to_bigint(
  table,
  columns,
  primary_key: :id,
  batch_size: 20_000,
  sub_batch_size: 1000,
  interval: 2.minutes
)

  unless table_exists?(table)
    raise "Table #{table} does not exist"
  end

  unless column_exists?(table, primary_key)
    raise "Column #{primary_key} does not exist on #{table}"
  end

  conversions = Array.wrap(columns).to_h do |column|
    raise ArgumentError, "Column #{column} does not exist on #{table}" unless column_exists?(table, column)

    temporary_name = convert_to_bigint_column(column)
    raise ArgumentError, "Column #{temporary_name} does not exist on #{table}" unless column_exists?(table, temporary_name)

    [column, temporary_name]
  end

  queue_batched_background_migration(
    'CopyColumnUsingBackgroundMigrationJob',
    table,
    primary_key,
    conversions.keys,
    conversions.values,
    job_interval: interval,
    batch_size: batch_size,
    sub_batch_size: sub_batch_size)
end

#backfill_iids(table) ⇒ Object

Note this should only be used with very small tables



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# File 'lib/gitlab/database/migration_helpers.rb', line 1058

def backfill_iids(table)
  sql = <<-END
    UPDATE #{table}
    SET iid = #{table}_with_calculated_iid.iid_num
    FROM (
      SELECT id, ROW_NUMBER() OVER (PARTITION BY project_id ORDER BY id ASC) AS iid_num FROM #{table}
    ) AS #{table}_with_calculated_iid
    WHERE #{table}.id = #{table}_with_calculated_iid.id
  END

  execute(sql)
end

#change_column_type_concurrently(table, column, new_type, type_cast_function: nil, batch_column_name: :id) ⇒ Object

Changes the type of a column concurrently.

table - The table containing the column. column - The name of the column to change. new_type - The new column type.



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# File 'lib/gitlab/database/migration_helpers.rb', line 549

def change_column_type_concurrently(table, column, new_type, type_cast_function: nil, batch_column_name: :id)
  temp_column = "#{column}_for_type_change"

  rename_column_concurrently(table, column, temp_column, type: new_type, type_cast_function: type_cast_function, batch_column_name: batch_column_name)
end

#check_trigger_permissions!(table) ⇒ Object 



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# File 'lib/gitlab/database/migration_helpers.rb', line 993

def check_trigger_permissions!(table)
  unless Grant.create_and_execute_trigger?(table)
    dbname = ApplicationRecord.database.database_name
    user = ApplicationRecord.database.username

    raise <<-EOF
Your database user is not allowed to create, drop, or execute triggers on the
table #{table}.

If you are using PostgreSQL you can solve this by logging in to the GitLab
database (#{dbname}) using a super user and running:

    ALTER #{user} WITH SUPERUSER

This query will grant the user super user permissions, ensuring you don't run
into similar problems in the future (e.g. when new tables are created).
    EOF
  end
end

#cleanup_concurrent_column_rename(table, old, new) ⇒ Object

Cleans up a concurrent column name.

This method takes care of removing previously installed triggers as well as removing the old column.

table - The name of the database table. old - The name of the old column. new - The name of the new column.



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# File 'lib/gitlab/database/migration_helpers.rb', line 651

def cleanup_concurrent_column_rename(table, old, new)
  trigger_name = rename_trigger_name(table, old, new)

  check_trigger_permissions!(table)

  remove_rename_triggers(table, trigger_name)

  remove_column(table, old)
end

#cleanup_concurrent_column_type_change(table, column) ⇒ Object

Performs cleanup of a concurrent type change.

table - The table containing the column. column - The name of the column to change. new_type - The new column type.



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# File 'lib/gitlab/database/migration_helpers.rb', line 570

def cleanup_concurrent_column_type_change(table, column)
  temp_column = "#{column}_for_type_change"

  transaction do
    # This has to be performed in a transaction as otherwise we might have
    # inconsistent data.
    cleanup_concurrent_column_rename(table, column, temp_column)
    rename_column(table, temp_column, column)
  end
end

#column_for(table, name) ⇒ Object

Returns the column for the given table and column name.



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# File 'lib/gitlab/database/migration_helpers.rb', line 951

def column_for(table, name)
  name = name.to_s

  column = columns(table).find { |column| column.name == name }
  raise(missing_schema_object_message(table, "column", name)) if column.nil?

  column
end

#concurrent_foreign_key_name(table, column, prefix: 'fk_') ⇒ Object

Returns the name for a concurrent foreign key.

PostgreSQL constraint names have a limit of 63 bytes. The logic used here is based on Rails’ foreign_key_name() method, which unfortunately is private so we can’t rely on it directly.

prefix:

  • The default prefix is ‘fk_` for backward compatibility with the existing

concurrent foreign key helpers.

  • For standard rails foreign keys the prefix is ‘fk_rails_`



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# File 'lib/gitlab/database/migration_helpers.rb', line 350

def concurrent_foreign_key_name(table, column, prefix: 'fk_')
  identifier = "#{table}_#{multiple_columns(column, separator: '_')}_fk"
  hashed_identifier = Digest::SHA256.hexdigest(identifier).first(10)

  "#{prefix}#{hashed_identifier}"
end

#convert_to_bigint_column(column) ⇒ Object 



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# File 'lib/gitlab/database/migration_helpers.rb', line 695

def convert_to_bigint_column(column)
  "#{column}_convert_to_bigint"
end

#convert_to_type_column(column, from_type, to_type) ⇒ Object 



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# File 'lib/gitlab/database/migration_helpers.rb', line 691

def convert_to_type_column(column, from_type, to_type)
  "#{column}_convert_#{from_type}_to_#{to_type}"
end

#copy_foreign_keys(table, old, new) ⇒ Object

Copies all foreign keys for the old column to the new column.

table - The table containing the columns and indexes. old - The old column. new - The new column.



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# File 'lib/gitlab/database/migration_helpers.rb', line 941

def copy_foreign_keys(table, old, new)
  foreign_keys_for(table, old).each do |fk|
    add_concurrent_foreign_key(fk.from_table,
                               fk.to_table,
                               column: new,
                               on_delete: fk.on_delete)
  end
end

#copy_indexes(table, old, new) ⇒ Object

Copies all indexes for the old column to a new column.

table - The table containing the columns and indexes. old - The old column. new - The new column.



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# File 'lib/gitlab/database/migration_helpers.rb', line 894

def copy_indexes(table, old, new)
  old = old.to_s
  new = new.to_s

  indexes_for(table, old).each do |index|
    new_columns = index.columns.map do |column|
      column == old ? new : column
    end

    # This is necessary as we can't properly rename indexes such as
    # "ci_taggings_idx".
    unless index.name.include?(old)
      raise "The index #{index.name} can not be copied as it does not "\
        "mention the old column. You have to rename this index manually first."
    end

    name = index.name.gsub(old, new)

    options = {
      unique: index.unique,
      name: name,
      length: index.lengths,
      order: index.orders
    }

    options[:using] = index.using if index.using
    options[:where] = index.where if index.where

    unless index.opclasses.blank?
      opclasses = index.opclasses.dup

      # Copy the operator classes for the old column (if any) to the new
      # column.
      opclasses[new] = opclasses.delete(old) if opclasses[old]

      options[:opclass] = opclasses
    end

    add_concurrent_index(table, new_columns, options)
  end
end

#create_or_update_plan_limit(limit_name, plan_name, limit_value) ⇒ Object 



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# File 'lib/gitlab/database/migration_helpers.rb', line 1045

def create_or_update_plan_limit(limit_name, plan_name, limit_value)
  limit_name_quoted = quote_column_name(limit_name)
  plan_name_quoted = quote(plan_name)
  limit_value_quoted = quote(limit_value)

  execute <<~SQL
    INSERT INTO plan_limits (plan_id, #{limit_name_quoted})
    SELECT id, #{limit_value_quoted} FROM plans WHERE name = #{plan_name_quoted} LIMIT 1
    ON CONFLICT (plan_id) DO UPDATE SET #{limit_name_quoted} = EXCLUDED.#{limit_name_quoted};
  SQL
end

#create_temporary_columns_and_triggers(table, mappings, primary_key: :id, old_bigint_column_naming: false) ⇒ Object

rubocop:disable Metrics/CyclomaticComplexity,Metrics/PerceivedComplexity

Raises:

  • (ArgumentError) 


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# File 'lib/gitlab/database/migration_helpers.rb', line 1100

def create_temporary_columns_and_triggers(table, mappings, primary_key: :id, old_bigint_column_naming: false)
  raise ArgumentError, "No mappings for column conversion provided" if mappings.blank?

  unless mappings.values.all? { |values| mapping_has_required_columns?(values) }
    raise ArgumentError, "Some mappings don't have required keys provided"
  end

  neutral_values_for_type = {
    int: 0,
    bigint: 0,
    uuid: '00000000-0000-0000-0000-000000000000'
  }

  unless table_exists?(table)
    raise "Table #{table} does not exist"
  end

  unless column_exists?(table, primary_key)
    raise "Column #{primary_key} does not exist on #{table}"
  end

  columns = mappings.keys
  columns.each do |column|
    next if column_exists?(table, column)

    raise ArgumentError, "Column #{column} does not exist on #{table}"
  end

  check_trigger_permissions!(table)

  if old_bigint_column_naming
    mappings.each do |column, params|
      params.merge!(
        temporary_column_name: convert_to_bigint_column(column)
      )
    end
  else
    mappings.each do |column, params|
      params.merge!(
        temporary_column_name: convert_to_type_column(column, params[:from_type], params[:to_type])
      )
    end
  end

  with_lock_retries do
    mappings.each do |(column_name, params)|
      column = column_for(table, column_name)
      temporary_name = params[:temporary_column_name]
      data_type = params[:to_type]
      default_value = params[:default_value]

      if (column.name.to_s == primary_key.to_s) || !column.null
        # If the column to be converted is either a PK or is defined as NOT NULL,
        # set it to `NOT NULL DEFAULT 0` and we'll copy paste the correct values bellow
        # That way, we skip the expensive validation step required to add
        #  a NOT NULL constraint at the end of the process
        add_column(
          table,
          temporary_name,
          data_type,
          default: column.default || default_value || neutral_values_for_type.fetch(data_type),
          null: false
        )
      else
        add_column(
          table,
          temporary_name,
          data_type,
          default: column.default
        )
      end
    end

    old_column_names = mappings.keys
    temporary_column_names = mappings.values.map { |v| v[:temporary_column_name] }
    install_rename_triggers(table, old_column_names, temporary_column_names)
  end
end

#define_batchable_model(table_name, connection: self.connection) ⇒ Object 



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# File 'lib/gitlab/database/migration_helpers.rb', line 21

def define_batchable_model(table_name, connection: self.connection)
  super(table_name, connection: connection)
end

#drop_sequence(table_name, column_name, sequence_name) ⇒ Object 



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# File 'lib/gitlab/database/migration_helpers.rb', line 1085

def drop_sequence(table_name, column_name, sequence_name)
  execute <<~SQL
    ALTER TABLE #{quote_table_name(table_name)} ALTER COLUMN #{quote_column_name(column_name)} DROP DEFAULT;
    DROP SEQUENCE IF EXISTS #{quote_table_name(sequence_name)}
  SQL
end

#each_batch(table_name, connection: self.connection, **kwargs) ⇒ Object 



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# File 'lib/gitlab/database/migration_helpers.rb', line 25

def each_batch(table_name, connection: self.connection, **kwargs)
  super(table_name, connection: connection, **kwargs)
end

#each_batch_range(table_name, connection: self.connection, **kwargs) ⇒ Object 



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# File 'lib/gitlab/database/migration_helpers.rb', line 29

def each_batch_range(table_name, connection: self.connection, **kwargs)
  super(table_name, connection: connection, **kwargs)
end

#false_value ⇒ Object 



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# File 'lib/gitlab/database/migration_helpers.rb', line 361

def false_value
  Database.false_value
end

#foreign_key_exists?(source, target = nil, **options) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/gitlab/database/migration_helpers.rb', line 307

def foreign_key_exists?(source, target = nil, **options)
  # This if block is necessary because foreign_key_exists? is called in down migrations that may execute before
  # the postgres_foreign_keys view had necessary columns added.
  # In that case, we revert to the previous behavior of this method.
  # The behavior in the if block has a bug: it always returns false if the fk being checked has multiple columns.
  # This can be removed after init_schema.rb passes 20221122210711_add_columns_to_postgres_foreign_keys.rb
  # Tracking issue: https://gitlab.com/gitlab-org/gitlab/-/issues/386796
  unless connection.column_exists?('postgres_foreign_keys', 'constrained_table_name')
    return foreign_keys(source).any? do |foreign_key|
      tables_match?(target.to_s, foreign_key.to_table.to_s) &&
          options_match?(foreign_key.options, options)
    end
  end

  # Since we may be migrating in one go from a previous version without
  # `constrained_table_name` then we may see that this column exists
  # (as above) but the schema cache is still outdated for the model.
  unless Gitlab::Database::PostgresForeignKey.column_names.include?('constrained_table_name')
    Gitlab::Database::PostgresForeignKey.reset_column_information
  end

  fks = Gitlab::Database::PostgresForeignKey.by_constrained_table_name_or_identifier(source)

  fks = fks.by_referenced_table_name(target) if target
  fks = fks.by_name(options[:name]) if options[:name]
  fks = fks.by_constrained_columns(options[:column]) if options[:column]
  fks = fks.by_referenced_columns(options[:primary_key]) if options[:primary_key]
  fks = fks.by_on_delete_action(options[:on_delete]) if options[:on_delete]

  fks.exists?
end

#foreign_keys_for(table, column) ⇒ Object

Returns an Array containing the foreign keys for the given column.



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# File 'lib/gitlab/database/migration_helpers.rb', line 883

def foreign_keys_for(table, column)
  column = column.to_s

  foreign_keys(table).select { |fk| fk.column == column }
end

#index_exists_by_name?(table, index) ⇒ Boolean

Fetches indexes on a column by name for postgres.

This will include indexes using an expression on the column, for example: ‘CREATE INDEX CONCURRENTLY index_name ON table (LOWER(column));`

We can remove this when upgrading to Rails 5 with an updated ‘index_exists?`:

Or this can be removed when we no longer support postgres < 9.5, so we can use ‘CREATE INDEX IF NOT EXISTS`.

Returns:

  • (Boolean) 


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# File 'lib/gitlab/database/migration_helpers.rb', line 1023

def index_exists_by_name?(table, index)
  # We can't fall back to the normal `index_exists?` method because that
  # does not find indexes without passing a column name.
  if indexes(table).map(&:name).include?(index.to_s)
    true
  else
    postgres_exists_by_name?(table, index)
  end
end

#index_invalid?(index_name, schema: nil) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/gitlab/database/migration_helpers.rb', line 129

def index_invalid?(index_name, schema: nil)
  index_name = connection.quote(index_name)
  schema = connection.quote(schema) if schema
  schema ||= 'current_schema()'

  connection.select_value(<<~SQL)
    select not i.indisvalid
    from pg_class c
    inner join pg_index i
      on c.oid = i.indexrelid
    inner join pg_namespace n
      on n.oid = c.relnamespace
    where n.nspname = #{schema}
      and c.relname = #{index_name}
  SQL
end

#indexes_for(table, column) ⇒ Object

Returns an Array containing the indexes for the given column



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# File 'lib/gitlab/database/migration_helpers.rb', line 876

def indexes_for(table, column)
  column = column.to_s

  indexes(table).select { |index| index.columns.include?(column) }
end

#initialize_conversion_of_integer_to_bigint(table, columns, primary_key: :id) ⇒ Object

Initializes the conversion of a set of integer columns to bigint

It can be used for converting both a Primary Key and any Foreign Keys that may reference it or any other integer column that we may want to upgrade (e.g. columns that store IDs, but are not set as FKs).

  • For primary keys and Foreign Keys (or other columns) defined as NOT NULL,

    the new bigint column is added with a hardcoded NOT NULL DEFAULT 0
which allows us to skip a very costly verification step once we
are ready to switch it.

    This is crucial for Primary Key conversions, because setting a column

    as the PK converts even check constraints to NOT NULL constraints
and forces an inline re-verification of the whole table.

  • It sets up a trigger to keep the two columns in sync.

    Note: this helper is intended to be used in a regular (pre-deployment) migration.

    This helper is part 1 of a multi-step migration process:

    1. initialize_conversion_of_integer_to_bigint to create the new columns and database trigger

    2. backfill_conversion_of_integer_to_bigint to copy historic data using background migrations

    3. remaining steps TBD, see #288005

table - The name of the database table containing the column columns - The name, or array of names, of the column(s) that we want to convert to bigint. primary_key - The name of the primary key column (most often :id)



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# File 'lib/gitlab/database/migration_helpers.rb', line 724

def initialize_conversion_of_integer_to_bigint(table, columns, primary_key: :id)
  mappings = Array(columns).map do |c|
    {
      c => {
        from_type: :int,
        to_type: :bigint,
        default_value: 0
      }
    }
  end.reduce(&:merge)

  create_temporary_columns_and_triggers(
    table,
    mappings,
    primary_key: primary_key,
    old_bigint_column_naming: true
  )
end

#install_rename_triggers(table, old, new, trigger_name: nil) ⇒ Object

Installs triggers in a table that keep a new column in sync with an old one.

table - The name of the table to install the trigger in. old_column - The name of the old column. new_column - The name of the new column. trigger_name - The name of the trigger to use (optional).



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# File 'lib/gitlab/database/migration_helpers.rb', line 530

def install_rename_triggers(table, old, new, trigger_name: nil)
  Gitlab::Database::UnidirectionalCopyTrigger.on_table(table, connection: connection).create(old, new, trigger_name: trigger_name)
end

#partition?(table_name) ⇒ Boolean

rubocop:enable Metrics/CyclomaticComplexity,Metrics/PerceivedComplexity

Returns:

  • (Boolean) 


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# File 'lib/gitlab/database/migration_helpers.rb', line 1180

def partition?(table_name)
  if view_exists?(:postgres_partitions)
    Gitlab::Database::PostgresPartition.partition_exists?(table_name)
  else
    Gitlab::Database::PostgresPartition.legacy_partition_exists?(table_name)
  end
end

#postgres_exists_by_name?(table, name) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/gitlab/database/migration_helpers.rb', line 1033

def postgres_exists_by_name?(table, name)
  index_sql = <<~SQL
    SELECT COUNT(*)
    FROM pg_catalog.pg_indexes
    WHERE schemaname = #{connection.quote(current_schema)}
      AND tablename = #{connection.quote(table)}
      AND indexname = #{connection.quote(name)}
  SQL

  connection.select_value(index_sql).to_i > 0
end

#remove_column_default(table_name, column_name) ⇒ Object

While it is safe to call ‘change_column_default` on a column without default it would still require access exclusive lock on the table and for tables with high autovacuum(wraparound prevention) it will fail if their executions overlap.



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# File 'lib/gitlab/database/migration_helpers.rb', line 1199

def remove_column_default(table_name, column_name)
  column = connection.columns(table_name).find { |col| col.name == column_name.to_s }

  if column.default || column.default_function
    change_column_default(table_name, column_name, to: nil)
  end
end

#remove_concurrent_index(table_name, column_name, options = {}) ⇒ Object

Removes an existed index, concurrently

Example:

remove_concurrent_index :users, :some_column

See Rails’ ‘remove_index` for more info on the available arguments.



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# File 'lib/gitlab/database/migration_helpers.rb', line 153

def remove_concurrent_index(table_name, column_name, options = {})
  if transaction_open?
    raise 'remove_concurrent_index can not be run inside a transaction, ' \
      'you can disable transactions by calling disable_ddl_transaction! ' \
      'in the body of your migration class'
  end

  if partition?(table_name)
    raise ArgumentError, 'remove_concurrent_index can not be used on a partitioned '  \
      'table. Please use remove_concurrent_partitioned_index_by_name on the partitioned table ' \
      'as we need to remove the index on the parent table'
  end

  options = options.merge({ algorithm: :concurrently })

  unless index_exists?(table_name, column_name, **options)
    Gitlab::AppLogger.warn "Index not removed because it does not exist (this may be due to an aborted migration or similar): table_name: #{table_name}, column_name: #{column_name}"
    return
  end

  disable_statement_timeout do
    remove_index(table_name, **options.merge({ column: column_name }))
  end

  # We removed this index. Now let's make sure it's not queued for async creation.
  unprepare_async_index(table_name, column_name, **options)
end

#remove_concurrent_index_by_name(table_name, index_name, options = {}) ⇒ Object

Removes an existing index, concurrently

Example:

remove_concurrent_index :users, "index_X_by_Y"

See Rails’ ‘remove_index` for more info on the available arguments.



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# File 'lib/gitlab/database/migration_helpers.rb', line 188

def remove_concurrent_index_by_name(table_name, index_name, options = {})
  if transaction_open?
    raise 'remove_concurrent_index_by_name can not be run inside a transaction, ' \
      'you can disable transactions by calling disable_ddl_transaction! ' \
      'in the body of your migration class'
  end

  if partition?(table_name)
    raise ArgumentError, 'remove_concurrent_index_by_name can not be used on a partitioned '  \
      'table. Please use remove_concurrent_partitioned_index_by_name on the partitioned table ' \
      'as we need to remove the index on the parent table'
  end

  index_name = index_name[:name] if index_name.is_a?(Hash)

  raise 'remove_concurrent_index_by_name must get an index name as the second argument' if index_name.blank?

  options = options.merge({ algorithm: :concurrently })

  unless index_exists_by_name?(table_name, index_name)
    Gitlab::AppLogger.warn "Index not removed because it does not exist (this may be due to an aborted migration or similar): table_name: #{table_name}, index_name: #{index_name}"
    return
  end

  disable_statement_timeout do
    remove_index(table_name, **options.merge({ name: index_name }))
  end

  # We removed this index. Now let's make sure it's not queued for async creation.
  unprepare_async_index_by_name(table_name, index_name, **options)
end

#remove_foreign_key_if_exists(source, target = nil, **kwargs) ⇒ Object 



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# File 'lib/gitlab/database/migration_helpers.rb', line 973

def remove_foreign_key_if_exists(source, target = nil, **kwargs)
  reverse_lock_order = kwargs.delete(:reverse_lock_order)
  return unless foreign_key_exists?(source, target, **kwargs)

  if target && reverse_lock_order && transaction_open?
    execute("LOCK TABLE #{target}, #{source} IN ACCESS EXCLUSIVE MODE")
  end

  if target
    remove_foreign_key(source, target, **kwargs)
  else
    remove_foreign_key(source, **kwargs)
  end
end

#remove_foreign_key_without_error(*args, **kwargs) ⇒ Object 



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# File 'lib/gitlab/database/migration_helpers.rb', line 988

def remove_foreign_key_without_error(*args, **kwargs)
  remove_foreign_key(*args, **kwargs)
rescue ArgumentError
end

#remove_rename_triggers(table, trigger) ⇒ Object

Removes the triggers used for renaming a column concurrently.



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# File 'lib/gitlab/database/migration_helpers.rb', line 535

def remove_rename_triggers(table, trigger)
  Gitlab::Database::UnidirectionalCopyTrigger.on_table(table, connection: connection).drop(trigger)
end

#remove_timestamps(table_name, options = {}) ⇒ Object

To be used in the ‘#down` method of migrations that use `#add_timestamps_with_timezone`.

Available options are:

:columns - the column names to remove. Must be one
           Default value: `DEFAULT_TIMESTAMP_COLUMNS`

All options are optional.



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# File 'lib/gitlab/database/migration_helpers.rb', line 77

def remove_timestamps(table_name, options = {})
  columns = options.fetch(:columns, DEFAULT_TIMESTAMP_COLUMNS)
  columns.each do |column_name|
    remove_column(table_name, column_name)
  end
end

#rename_column_concurrently(table, old, new, type: nil, type_cast_function: nil, batch_column_name: :id) ⇒ Object

Renames a column without requiring downtime.

Concurrent renames work by using database triggers to ensure both the old and new column are in sync. However, this method will not remove the triggers or the old column automatically; this needs to be done manually in a post-deployment migration. This can be done using the method ‘cleanup_concurrent_column_rename`.

table - The name of the database table containing the column. old - The old column name. new - The new column name. type - The type of the new column. If no type is given the old column’s

type is used.

batch_column_name - option is for tables without primary key, in this

case another unique integer column can be used. Example: :user_id



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# File 'lib/gitlab/database/migration_helpers.rb', line 489

def rename_column_concurrently(table, old, new, type: nil, type_cast_function: nil, batch_column_name: :id)
  unless column_exists?(table, batch_column_name)
    raise "Column #{batch_column_name} does not exist on #{table}"
  end

  if transaction_open?
    raise 'rename_column_concurrently can not be run inside a transaction'
  end

  check_trigger_permissions!(table)

  create_column_from(table, old, new, type: type, batch_column_name: batch_column_name, type_cast_function: type_cast_function)

  install_rename_triggers(table, old, new)
end

#rename_trigger_name(table, old, new) ⇒ Object

Returns the (base) name to use for triggers when renaming columns.



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# File 'lib/gitlab/database/migration_helpers.rb', line 540

def rename_trigger_name(table, old, new)
  Gitlab::Database::UnidirectionalCopyTrigger.on_table(table, connection: connection).name(old, new)
end

#replace_sql(column, pattern, replacement) ⇒ Object

This will replace the first occurrence of a string in a column with the replacement using ‘regexp_replace`



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# File 'lib/gitlab/database/migration_helpers.rb', line 962

def replace_sql(column, pattern, replacement)
  quoted_pattern = Arel::Nodes::Quoted.new(pattern.to_s)
  quoted_replacement = Arel::Nodes::Quoted.new(replacement.to_s)

  replace = Arel::Nodes::NamedFunction.new(
    "regexp_replace", [column, quoted_pattern, quoted_replacement]
  )

  Arel::Nodes::SqlLiteral.new(replace.to_sql)
end

#restore_conversion_of_integer_to_bigint(table, columns, primary_key: :id) ⇒ Object

Reverts ‘cleanup_conversion_of_integer_to_bigint`

table - The name of the database table containing the columns columns - The name, or array of names, of the column(s) that we have converted to bigint. primary_key - The name of the primary key column (most often :id)



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# File 'lib/gitlab/database/migration_helpers.rb', line 763

def restore_conversion_of_integer_to_bigint(table, columns, primary_key: :id)
  mappings = Array(columns).map do |c|
    {
      c => {
        from_type: :bigint,
        to_type: :int,
        default_value: 0
      }
    }
  end.reduce(&:merge)

  create_temporary_columns_and_triggers(
    table,
    mappings,
    primary_key: primary_key,
    old_bigint_column_naming: true
  )
end

#revert_backfill_conversion_of_integer_to_bigint(table, columns, primary_key: :id) ⇒ Object

Reverts ‘backfill_conversion_of_integer_to_bigint`

table - The name of the database table containing the column columns - The name, or an array of names, of the column(s) we want to convert to bigint. primary_key - The name of the primary key column (most often :id)



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# File 'lib/gitlab/database/migration_helpers.rb', line 860

def revert_backfill_conversion_of_integer_to_bigint(table, columns, primary_key: :id)
  columns = Array.wrap(columns)

  conditions = ActiveRecord::Base.sanitize_sql(
    [
      'job_class_name = :job_class_name AND table_name = :table_name AND column_name = :column_name AND job_arguments = :job_arguments',
      job_class_name: 'CopyColumnUsingBackgroundMigrationJob',
      table_name: table,
      column_name: primary_key,
      job_arguments: [columns, columns.map { |column| convert_to_bigint_column(column) }].to_json
    ])

  execute("DELETE FROM batched_background_migrations WHERE #{conditions}")
end

#revert_initialize_conversion_of_integer_to_bigint(table, columns) ⇒ Object Also known as: cleanup_conversion_of_integer_to_bigint

Reverts ‘initialize_conversion_of_integer_to_bigint`

table - The name of the database table containing the columns columns - The name, or array of names, of the column(s) that we’re converting to bigint.



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# File 'lib/gitlab/database/migration_helpers.rb', line 747

def revert_initialize_conversion_of_integer_to_bigint(table, columns)
  columns = Array.wrap(columns)
  temporary_columns = columns.map { |column| convert_to_bigint_column(column) }

  trigger_name = rename_trigger_name(table, columns, temporary_columns)
  remove_rename_triggers(table, trigger_name)

  temporary_columns.each { |column| remove_column(table, column) }
end

#swap_primary_key(table_name, primary_key_name, index_to_use) ⇒ Object Also known as: unswap_primary_key 



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# File 'lib/gitlab/database/migration_helpers.rb', line 1077

def swap_primary_key(table_name, primary_key_name, index_to_use)
  with_lock_retries(raise_on_exhaustion: true) do
    drop_constraint(table_name, primary_key_name, cascade: true)
    add_primary_key_using_index(table_name, primary_key_name, index_to_use)
  end
end

#table_partitioned?(table_name) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/gitlab/database/migration_helpers.rb', line 1188

def table_partitioned?(table_name)
  Gitlab::Database::PostgresPartitionedTable
    .find_by_name_in_current_schema(table_name)
    .present?
end

#true_value ⇒ Object 



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# File 'lib/gitlab/database/migration_helpers.rb', line 357

def true_value
  Database.true_value
end

#undo_change_column_type_concurrently(table, column) ⇒ Object

Reverses operations performed by change_column_type_concurrently.

table - The table containing the column. column - The name of the column to change.



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# File 'lib/gitlab/database/migration_helpers.rb', line 559

def undo_change_column_type_concurrently(table, column)
  temp_column = "#{column}_for_type_change"

  undo_rename_column_concurrently(table, column, temp_column)
end

#undo_cleanup_concurrent_column_rename(table, old, new, type: nil, batch_column_name: :id) ⇒ Object

Reverses the operations performed by cleanup_concurrent_column_rename.

This method adds back the old_column removed by cleanup_concurrent_column_rename. It also adds back the (old_column > new_column) trigger that is removed by cleanup_concurrent_column_rename.

table - The name of the database table containing the column. old - The old column name. new - The new column name. type - The type of the old column. If no type is given the new column’s

type is used.

batch_column_name - option is for tables without primary key, in this

case another unique integer column can be used. Example: :user_id



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# File 'lib/gitlab/database/migration_helpers.rb', line 675

def undo_cleanup_concurrent_column_rename(table, old, new, type: nil, batch_column_name: :id)
  unless column_exists?(table, batch_column_name)
    raise "Column #{batch_column_name} does not exist on #{table}"
  end

  if transaction_open?
    raise 'undo_cleanup_concurrent_column_rename can not be run inside a transaction'
  end

  check_trigger_permissions!(table)

  create_column_from(table, new, old, type: type, batch_column_name: batch_column_name)

  install_rename_triggers(table, old, new)
end

#undo_cleanup_concurrent_column_type_change(table, column, old_type, type_cast_function: nil, batch_column_name: :id, limit: nil) ⇒ Object

Reverses operations performed by cleanup_concurrent_column_type_change.

table - The table containing the column. column - The name of the column to change. old_type - The type of the original column used with change_column_type_concurrently. type_cast_function - Required if the conversion back to the original type is not automatic batch_column_name - option for tables without a primary key, in this case

another unique integer column can be used. Example: :user_id



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# File 'lib/gitlab/database/migration_helpers.rb', line 589

def undo_cleanup_concurrent_column_type_change(table, column, old_type, type_cast_function: nil, batch_column_name: :id, limit: nil)
  Gitlab::Database::QueryAnalyzers::RestrictAllowedSchemas.require_ddl_mode!

  temp_column = "#{column}_for_type_change"

  # Using a descriptive name that includes orinal column's name risks
  # taking us above the 63 character limit, so we use a hash
  identifier = "#{table}_#{column}_for_type_change"
  hashed_identifier = Digest::SHA256.hexdigest(identifier).first(10)
  temp_undo_cleanup_column = "tmp_undo_cleanup_column_#{hashed_identifier}"

  unless column_exists?(table, batch_column_name)
    raise "Column #{batch_column_name} does not exist on #{table}"
  end

  if transaction_open?
    raise 'undo_cleanup_concurrent_column_type_change can not be run inside a transaction'
  end

  check_trigger_permissions!(table)

  begin
    create_column_from(
      table,
      column,
      temp_undo_cleanup_column,
      type: old_type,
      batch_column_name: batch_column_name,
      type_cast_function: type_cast_function,
      limit: limit
    )

    transaction do
      # This has to be performed in a transaction as otherwise we might
      # have inconsistent data.
      rename_column(table, column, temp_column)
      rename_column(table, temp_undo_cleanup_column, column)

      install_rename_triggers(table, column, temp_column)
    end
  rescue StandardError
    # create_column_from can not run inside a transaction, which means
    #  that there is a risk that if any of the operations that follow it
    #  fail, we'll be left with an inconsistent schema
    # For those reasons, we make sure that we drop temp_undo_cleanup_column
    #  if an error is caught
    if column_exists?(table, temp_undo_cleanup_column)
      remove_column(table, temp_undo_cleanup_column)
    end

    raise
  end
end

#undo_rename_column_concurrently(table, old, new) ⇒ Object

Reverses operations performed by rename_column_concurrently.

This method takes care of removing previously installed triggers as well as removing the new column.

table - The name of the database table. old - The name of the old column. new - The name of the new column.



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# File 'lib/gitlab/database/migration_helpers.rb', line 513

def undo_rename_column_concurrently(table, old, new)
  trigger_name = rename_trigger_name(table, old, new)

  check_trigger_permissions!(table)

  remove_rename_triggers(table, trigger_name)

  remove_column(table, new)
end

#update_column_in_batches(table_name, column, value, batch_size: nil, batch_column_name: :id, disable_lock_writes: false) ⇒ Object

Updates the value of a column in batches.

This method updates the table in batches of 5% of the total row count. A ‘batch_size` option can also be passed to set this to a fixed number. This method will continue updating rows until no rows remain.

When given a block this method will yield two values to the block:

  1. An instance of ‘Arel::Table` for the table that is being updated.

  2. The query to run as an Arel object.

By supplying a block one can add extra conditions to the queries being executed. Note that the same block is used for all queries.

Example:

update_column_in_batches(:projects, :foo, 10) do |table, query|
  query.where(table[:some_column].eq('hello'))
end

This would result in this method updating only rows where ‘projects.some_column` equals “hello”.

table - The name of the table. column - The name of the column to update. value - The value for the column.

The ‘value` argument is typically a literal. To perform a computed update, an Arel literal can be used instead:

update_value = Arel.sql('bar * baz')

update_column_in_batches(:projects, :foo, update_value) do |table, query|
  query.where(table[:some_column].eq('hello'))
end

Rubocop’s Metrics/AbcSize metric is disabled for this method as Rubocop determines this method to be too complex while there’s no way to make it less “complex” without introducing extra methods (which actually will make things more complex).

‘batch_column_name` option is for tables without primary key, in this case another unique integer column can be used. Example: :user_id

rubocop: disable Metrics/AbcSize



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# File 'lib/gitlab/database/migration_helpers.rb', line 410

def update_column_in_batches(table_name, column, value, batch_size: nil, batch_column_name: :id, disable_lock_writes: false)
  if transaction_open?
    raise 'update_column_in_batches can not be run inside a transaction, ' \
      'you can disable transactions by calling disable_ddl_transaction! ' \
      'in the body of your migration class'
  end

  table = Arel::Table.new(table_name)

  count_arel = table.project(Arel.star.count.as('count'))
  count_arel = yield table, count_arel if block_given?

  total = exec_query(count_arel.to_sql).to_a.first['count'].to_i

  return if total == 0

  if batch_size.nil?
    # Update in batches of 5% until we run out of any rows to update.
    batch_size = ((total / 100.0) * 5.0).ceil
    max_size = 1000

    # The upper limit is 1000 to ensure we don't lock too many rows. For
    # example, for "merge_requests" even 1% of the table is around 35 000
    # rows for GitLab.com.
    batch_size = max_size if batch_size > max_size
  end

  start_arel = table.project(table[batch_column_name]).order(table[batch_column_name].asc).take(1)
  start_arel = yield table, start_arel if block_given?
  start_id = exec_query(start_arel.to_sql).to_a.first[batch_column_name.to_s].to_i

  loop do
    stop_arel = table.project(table[batch_column_name])
      .where(table[batch_column_name].gteq(start_id))
      .order(table[batch_column_name].asc)
      .take(1)
      .skip(batch_size)

    stop_arel = yield table, stop_arel if block_given?
    stop_row = exec_query(stop_arel.to_sql).to_a.first

    update_arel = Arel::UpdateManager.new
      .table(table)
      .set([[table[column], value]])
      .where(table[batch_column_name].gteq(start_id))

    if stop_row
      stop_id = stop_row[batch_column_name.to_s].to_i
      start_id = stop_id
      update_arel = update_arel.where(table[batch_column_name].lt(stop_id))
    end

    update_arel = yield table, update_arel if block_given?

    transaction do
      execute("SELECT set_config('lock_writes.#{table_name}', 'false', true)") if disable_lock_writes
      execute(update_arel.to_sql)
    end

    # There are no more rows left to update.
    break unless stop_row
  end
end

#validate_foreign_key(source, column, name: nil) ⇒ Object 



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# File 'lib/gitlab/database/migration_helpers.rb', line 295

def validate_foreign_key(source, column, name: nil)
  fk_name = name || concurrent_foreign_key_name(source, column)

  unless foreign_key_exists?(source, name: fk_name)
    raise missing_schema_object_message(source, "foreign key", fk_name)
  end

  disable_statement_timeout do
    execute("ALTER TABLE #{source} VALIDATE CONSTRAINT #{fk_name};")
  end
end