Module: Gitlab::Database::Migrations::TimeoutHelpers

Included in:
Gitlab::Database::MigrationHelpers, ConstraintsHelpers
Defined in:
lib/gitlab/database/migrations/timeout_helpers.rb

Instance Method Summary collapse

Instance Method Details

#disable_statement_timeout ⇒ Object

Long-running migrations may take more than the timeout allowed by the database. Disable the session’s statement timeout to ensure migrations don’t get killed prematurely.

There are two possible ways to disable the statement timeout:

  • Per transaction (this is the preferred and default mode)

  • Per connection (requires a cleanup after the execution)

When using a per connection disable statement, code must be inside a block so we can automatically execute ‘RESET statement_timeout` after block finishes otherwise the statement will still be disabled until connection is dropped or `RESET statement_timeout` is executed



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# File 'lib/gitlab/database/migrations/timeout_helpers.rb', line 20

def disable_statement_timeout
  if block_given?
    if statement_timeout_disabled?
      # Don't do anything if the statement_timeout is already disabled
      # Allows for nested calls of disable_statement_timeout without
      # resetting the timeout too early (before the outer call ends)
      yield
    else
      begin
        execute('SET statement_timeout TO 0')

        yield
      ensure
        execute('RESET statement_timeout')
      end
    end
  else
    unless transaction_open?
      raise <<~ERROR
        Cannot call disable_statement_timeout() without a transaction open or outside of a transaction block.
        If you don't want to use a transaction wrap your code in a block call:

        disable_statement_timeout { # code that requires disabled statement here }

        This will make sure statement_timeout is disabled before and reset after the block execution is finished.
      ERROR
    end

    execute('SET LOCAL statement_timeout TO 0')
  end
end