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
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