psql: add \dconfig command to show server's configuration parameters.

Plain \dconfig is basically equivalent to SHOW except that you can
give it a pattern with wildcards, either to match multiple GUCs or
because you don't exactly remember the name you want.

\dconfig+ adds type, context, and access-privilege information,
mainly because every other kind of object privilege has a psql command
to show it, so GUC privileges should too.  (A form of this command was
in some versions of the patch series leading up to commit a0ffa885e.
We pulled it out then because of doubts that the design and code were
up to snuff, but I think subsequent work has resolved that.)

In passing, fix incorrect completion of GUC names in GRANT/REVOKE
ON PARAMETER: a0ffa885e neglected to use the VERBATIM form of
COMPLETE_WITH_QUERY, so it misbehaved for custom (qualified) GUC
names.

Mark Dilger and Tom Lane

Discussion: https://postgr.es/m/[email protected]

1 files changed, 62 insertions, 0 deletions

diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index 3f1b3802c22..797ef233c90 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -4365,6 +4365,68 @@ listConversions(const char *pattern, bool verbose, bool showSystem)
 }
 
 /*
+ * \dconfig
+ *
+ * Describes configuration parameters.
+ */
+bool
+describeConfigurationParameters(const char *pattern, bool verbose,
+								bool showSystem)
+{
+	PQExpBufferData buf;
+	PGresult   *res;
+	printQueryOpt myopt = pset.popt;
+
+	initPQExpBuffer(&buf);
+	printfPQExpBuffer(&buf,
+					  "SELECT s.name AS \"%s\", "
+					  "pg_catalog.current_setting(s.name) AS \"%s\"",
+					  gettext_noop("Parameter"),
+					  gettext_noop("Value"));
+
+	if (verbose)
+	{
+		appendPQExpBuffer(&buf,
+						  ", s.vartype AS \"%s\", s.context AS \"%s\", ",
+						  gettext_noop("Type"),
+						  gettext_noop("Context"));
+		if (pset.sversion >= 150000)
+			printACLColumn(&buf, "p.paracl");
+		else
+			appendPQExpBuffer(&buf, "NULL AS \"%s\"",
+							  gettext_noop("Access privileges"));
+	}
+
+	appendPQExpBufferStr(&buf, "\nFROM pg_catalog.pg_settings s\n");
+
+	if (verbose && pset.sversion >= 150000)
+		appendPQExpBufferStr(&buf,
+							 "  LEFT JOIN pg_catalog.pg_parameter_acl p\n"
+							 "  ON pg_catalog.lower(s.name) = p.parname\n");
+
+	processSQLNamePattern(pset.db, &buf, pattern,
+						  false, false,
+						  NULL, "pg_catalog.lower(s.name)", NULL,
+						  NULL);
+
+	appendPQExpBufferStr(&buf, "ORDER BY 1;");
+
+	res = PSQLexec(buf.data);
+	termPQExpBuffer(&buf);
+	if (!res)
+		return false;
+
+	myopt.nullPrint = NULL;
+	myopt.title = _("List of configuration parameters");
+	myopt.translate_header = true;
+
+	printQuery(res, &myopt, pset.queryFout, false, pset.logfile);
+
+	PQclear(res);
+	return true;
+}
+
+/*
  * \dy
  *
  * Describes Event Triggers.