Does PostgreSQL support standard conforming strings?
# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 293
def supports_standard_conforming_strings?
# Temporarily set the client message level above error to prevent unintentional
# error messages in the logs when working on a PostgreSQL database server that
# does not support standard conforming strings.
client_min_messages_old = client_min_messages
self.client_min_messages = 'panic'
# postgres-pr does not raise an exception when client_min_messages is set higher
# than error and "SHOW standard_conforming_strings" fails, but returns an empty
# PGresult instead.
has_support = execute('SHOW standard_conforming_strings')[0][0] rescue false
self.client_min_messages = client_min_messages_old
has_support
end