According to the manual, backend sends a parameter status message when certain configuration variable has been changed and SIGHUP signal is sent. https://www.postgresql.org/docs/10/static/protocol-flow.html#PROTOCOL-ASYNC
ParameterStatus messages will be generated whenever the active value changes for any of the parameters the backend believes the frontend should know about. Most commonly this occurs in response to a SET SQL command executed by the frontend, and this case is effectively synchronous ― but it is also possible for parameter status changes to occur because the administrator changed a configuration file and then sent the SIGHUP signal to the server. So I connected to PostgreSQL using psql and attached strace to psql. Then I changed standard_conforming_strings and executed pg_ctl reload. The PostgreSQL log shows: 12073 2018-02-14 11:05:22 JST LOG: received SIGHUP, reloading configuration files 12073 2018-02-14 11:05:22 JST LOG: parameter "standard_conforming_strings" changed to "off" 12073 2018-02-14 11:05:22 JST DEBUG: sending signal 1 to process 12158 But as far as strace tells, nothing was sent to psql. Is this expected? Best regards, -- Tatsuo Ishii SRA OSS, Inc. Japan English: http://www.sraoss.co.jp/index_en.php Japanese:http://www.sraoss.co.jp
