[PATCH 1/3] Add \dX command on psql

Tatsuro Yamada <yamatattsu@gmail.com>

From: Tatsuro Yamada <yamatattsu@gmail.com>
To:
Date: 2020-11-09T02:25:14Z
Lists: pgsql-hackers
---
 doc/src/sgml/ref/psql-ref.sgml |  14 +++++
 src/bin/psql/command.c         |   3 +
 src/bin/psql/describe.c        | 100 +++++++++++++++++++++++++++++++++
 src/bin/psql/describe.h        |   3 +
 src/bin/psql/help.c            |   1 +
 src/bin/psql/tab-complete.c    |   4 +-
 6 files changed, 124 insertions(+), 1 deletion(-)

diff --git a/doc/src/sgml/ref/psql-ref.sgml b/doc/src/sgml/ref/psql-ref.sgml
index 221a967bfe..fd860776af 100644
--- a/doc/src/sgml/ref/psql-ref.sgml
+++ b/doc/src/sgml/ref/psql-ref.sgml
@@ -1918,6 +1918,20 @@ testdb=&gt;
         </para>
         </listitem>
       </varlistentry>
+      
+      <varlistentry>
+        <term><literal>\dX [ <link linkend="app-psql-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
+        <listitem>
+        <para>
+        Lists extended statistics.
+        If <replaceable class="parameter">pattern</replaceable>
+        is specified, only those extended statistics whose names match the pattern
+        are listed.
+        If <literal>+</literal> is appended to the command name, each extended statistics
+        is listed with its size.
+        </para>
+        </listitem>
+      </varlistentry>
 
       <varlistentry>
         <term><literal>\dy[+] [ <link linkend="app-psql-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
diff --git a/src/bin/psql/command.c b/src/bin/psql/command.c
index c7a83d5dfc..c6f1653cb7 100644
--- a/src/bin/psql/command.c
+++ b/src/bin/psql/command.c
@@ -930,6 +930,9 @@ exec_command_d(PsqlScanState scan_state, bool active_branch, const char *cmd)
 				else
 					success = listExtensions(pattern);
 				break;
+			case 'X':			/* Extended Statistics */
+				success = listExtendedStats(pattern, show_verbose);
+				break;
 			case 'y':			/* Event Triggers */
 				success = listEventTriggers(pattern, show_verbose);
 				break;
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index 07d640021c..1807324542 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -4397,6 +4397,106 @@ listEventTriggers(const char *pattern, bool verbose)
 	return true;
 }
 
+/*
+ * \dX
+ *
+ * Briefly describes extended statistics.
+ */
+bool
+listExtendedStats(const char *pattern, bool verbose)
+{
+	PQExpBufferData buf;
+	PGresult   *res;
+	printQueryOpt myopt = pset.popt;
+
+	if (pset.sversion < 100000)
+	{
+		char		sverbuf[32];
+
+		pg_log_error("The server (version %s) does not support extended statistics.",
+					 formatPGVersionNumber(pset.sversion, false,
+										   sverbuf, sizeof(sverbuf)));
+		return true;
+	}
+
+	initPQExpBuffer(&buf);
+	printfPQExpBuffer(&buf,
+					  "SELECT \n"
+					  "es.stxnamespace::pg_catalog.regnamespace::text AS \"%s\", \n"
+					  "es.stxname AS \"%s\", \n"
+					  "pg_catalog.format('%%s FROM %%s', \n"
+					  "  (SELECT pg_catalog.string_agg(pg_catalog.quote_ident(a.attname),', ') \n"
+					  "   FROM pg_catalog.unnest(es.stxkeys) s(attnum) \n"
+					  "   JOIN pg_catalog.pg_attribute a \n"
+					  "   ON (es.stxrelid = a.attrelid \n"
+					  "   AND a.attnum = s.attnum \n"
+					  "   AND NOT a.attisdropped)), \n"
+					  "es.stxrelid::regclass) AS \"%s\", \n"
+					  "CASE WHEN esd.stxdndistinct IS NOT NULL THEN 'built' \n"
+					  "     WHEN 'd' = any(es.stxkind) THEN 'defined' \n"
+					  "END AS \"%s\", \n"
+					  "CASE WHEN esd.stxddependencies IS NOT NULL THEN 'built' \n"
+					  "     WHEN 'f' = any(es.stxkind) THEN 'defined' \n"
+					  "END AS \"%s\", \n"
+					  "CASE WHEN esd.stxdmcv IS NOT NULL THEN 'built' \n"
+					  "     WHEN 'm' = any(es.stxkind) THEN 'defined' \n"
+					  "END AS \"%s\"",
+					  gettext_noop("Schema"),
+					  gettext_noop("Name"),
+					  gettext_noop("Definition"),
+					  gettext_noop("N_distinct"),
+					  gettext_noop("Dependencies"),
+					  gettext_noop("Mcv"));
+
+	if (verbose)
+	{
+		appendPQExpBuffer(&buf,
+						  ",\nCASE WHEN esd.stxdndistinct IS NOT NULL THEN \n"
+						  "          pg_catalog.pg_size_pretty(pg_catalog.length(stxdndistinct)::bigint) \n"
+						  "     WHEN 'd' = any(stxkind) THEN '0 bytes' \n"
+						  "END AS \"%s\", \n"
+						  "CASE WHEN esd.stxddependencies IS NOT NULL THEN \n"
+						  "          pg_catalog.pg_size_pretty(pg_catalog.length(stxddependencies)::bigint) \n"
+						  "     WHEN 'f' = any(stxkind) THEN '0 bytes' \n"
+						  "END AS \"%s\", \n"
+						  "CASE WHEN esd.stxdmcv IS NOT NULL THEN \n"
+						  "          pg_catalog.pg_size_pretty(pg_catalog.length(stxdmcv)::bigint) \n"
+						  "     WHEN 'm' = any(stxkind) THEN '0 bytes' \n"
+						  "END AS \"%s\" ",
+						  gettext_noop("N_size"),
+						  gettext_noop("D_size"),
+						  gettext_noop("M_size"));
+	}
+
+	appendPQExpBufferStr(&buf,
+						 " \nFROM pg_catalog.pg_statistic_ext es \n"
+						 "LEFT JOIN pg_catalog.pg_statistic_ext_data esd \n"
+						 "ON es.oid = esd.stxoid \n"
+						 "INNER JOIN pg_catalog.pg_class c \n"
+						 "ON es.stxrelid = c.oid \n");
+
+	processSQLNamePattern(pset.db, &buf, pattern, false,
+						  false, NULL,
+						  "stxname", NULL,
+						  NULL);
+
+	appendPQExpBufferStr(&buf, "ORDER BY 1, 2;");
+
+	res = PSQLexec(buf.data);
+	termPQExpBuffer(&buf);
+	if (!res)
+		return false;
+
+	myopt.nullPrint = NULL;
+	myopt.title = _("List of extended statistics");
+	myopt.translate_header = true;
+
+	printQuery(res, &myopt, pset.queryFout, false, pset.logfile);
+
+	PQclear(res);
+	return true;
+}
+
 /*
  * \dC
  *
diff --git a/src/bin/psql/describe.h b/src/bin/psql/describe.h
index f0e3ec957c..89b13c3f0c 100644
--- a/src/bin/psql/describe.h
+++ b/src/bin/psql/describe.h
@@ -102,6 +102,9 @@ extern bool listExtensions(const char *pattern);
 /* \dx+ */
 extern bool listExtensionContents(const char *pattern);
 
+/* \dX */
+extern bool listExtendedStats(const char *pattern, bool verbose);
+
 /* \dy */
 extern bool listEventTriggers(const char *pattern, bool verbose);
 
diff --git a/src/bin/psql/help.c b/src/bin/psql/help.c
index af829282e6..ea249bf96d 100644
--- a/src/bin/psql/help.c
+++ b/src/bin/psql/help.c
@@ -267,6 +267,7 @@ slashUsage(unsigned short int pager)
 	fprintf(output, _("  \\du[S+] [PATTERN]      list roles\n"));
 	fprintf(output, _("  \\dv[S+] [PATTERN]      list views\n"));
 	fprintf(output, _("  \\dx[+]  [PATTERN]      list extensions\n"));
+	fprintf(output, _("  \\dX[+]  [PATTERN]      list extended statistics\n"));
 	fprintf(output, _("  \\dy     [PATTERN]      list event triggers\n"));
 	fprintf(output, _("  \\l[+]   [PATTERN]      list databases\n"));
 	fprintf(output, _("  \\sf[+]  FUNCNAME       show a function's definition\n"));
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 5238a960f7..30a8ada7d2 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -1500,7 +1500,7 @@ psql_completion(const char *text, int start, int end)
 		"\\dF", "\\dFd", "\\dFp", "\\dFt", "\\dg", "\\di", "\\dl", "\\dL",
 		"\\dm", "\\dn", "\\do", "\\dO", "\\dp", "\\dP", "\\dPi", "\\dPt",
 		"\\drds", "\\dRs", "\\dRp", "\\ds", "\\dS",
-		"\\dt", "\\dT", "\\dv", "\\du", "\\dx", "\\dy",
+		"\\dt", "\\dT", "\\dv", "\\du", "\\dx", "\\dX", "\\dy",
 		"\\e", "\\echo", "\\ef", "\\elif", "\\else", "\\encoding",
 		"\\endif", "\\errverbose", "\\ev",
 		"\\f",
@@ -3851,6 +3851,8 @@ psql_completion(const char *text, int start, int end)
 		COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_views, NULL);
 	else if (TailMatchesCS("\\dx*"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_extensions);
+	else if (TailMatchesCS("\\dX*"))
+		COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_statistics, NULL);
 	else if (TailMatchesCS("\\dm*"))
 		COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_matviews, NULL);
 	else if (TailMatchesCS("\\dE*"))
-- 
2.26.2


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