Hackers, Over in Bug# 16652 [1] Christoph failed to recognize the fact that signal sending functions are inherently one-way just as signals are. It seems worth heading off this situation in the future by making it clear how signals behave and, in the specific case of pg_reload_conf, that the important feedback one would hope to get out of a success/failure response from the function call must instead be found in other locations.
Please see the attached patch, included inline as well. David J. [1] https://www.postgresql.org/message-id/flat/16652-58dd6028047058a6%40postgresql.org commit 6f0ba7c8fd131c906669882e4402930e548e4522 Author: David G. Johnston <david.g.johns...@gmail.com> Date: Mon Oct 12 22:35:38 2020 +0000 Clarify that signal functions have no feedback Bug# 16652 complains that the definition of success for pg_reload_conf doesn't include the outcome of actually reloading the configuration files. While this is a fairly easy gap to cross given knowledge of signals, being more explicit here doesn't hurt. Additionally, because of the special nature of pg_reload_conf, add links to the various locations where information related to the success or failure of a reload can be found. Lacking an existing holistic location in the documentation to point the reader just list the three resources explicitly. diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index e7cff980dd..75ff8acc93 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -23927,7 +23927,8 @@ SELECT collation for ('foo' COLLATE "de_DE"); <para> The functions shown in <xref - linkend="functions-admin-signal-table"/> send control signals to + linkend="functions-admin-signal-table"/> send uni-directional + control signals to other server processes. Use of these functions is restricted to superusers by default but access may be granted to others using <command>GRANT</command>, with noted exceptions. @@ -23935,7 +23936,8 @@ SELECT collation for ('foo' COLLATE "de_DE"); <para> Each of these functions returns <literal>true</literal> if - successful and <literal>false</literal> otherwise. + the signal was successfully sent and <literal>false</literal> + if the sending of the signal failed. </para> <table id="functions-admin-signal-table"> @@ -23983,7 +23985,14 @@ SELECT collation for ('foo' COLLATE "de_DE"); server to reload their configuration files. (This is initiated by sending a <systemitem>SIGHUP</systemitem> signal to the postmaster process, which in turn sends <systemitem>SIGHUP</systemitem> to each - of its children.) + of its children.) Inspection of the + <link linkend="runtime-config-logging">log file</link>, + <link linkend="view-pg-file-settings">pg_file_settings view</link>, + and the + <link linkend="view-pg-settings">pg_settings view</link>, + is recommended before and/or after executing + this function to detect whether there are any issues in the configuration + files preventing some of all of their setting changes from taking effect. </para></entry> </row>
v1-doc-pg-reload-conf-signaling.patch
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