Control plan format via GUC variable

Now you can select plan format by assigning to
'pg_show_plans.plan_format' GUC variable.

Close #31.

Author: kovmir

Makefile

@@ -3,7 +3,8 @@ OBJS = pg_show_plans.o
 
 EXTENSION = pg_show_plans
 DATA = pg_show_plans--1.0--1.1.sql \
-       pg_show_plans--1.1.sql
+       pg_show_plans--1.1--2.0.sql \
+       pg_show_plans--2.0.sql
 REGRESS = pg_show_plans formats
 DOCS = pg_show_plans.md
 

README.md

@@ -136,7 +136,3 @@ query |
   - `plan`: query plan.
 * `pg_show_plans_disable()`: disable extension.
 * `pg_show_plans_enable()`: enable extension.
-* `pgsp_format_text()`: changes query format to `json`.
-* `pgsp_format_json()`: changes query format to `json`.
-* `pgsp_format_yaml()`: changes query format to `yaml`.
-* `pgsp_format_xml()`: changes query format to `xml`.

expected/formats.out

@@ -6,12 +6,7 @@ select setting::int < 140000 as pg12_13 from pg_settings where name = 'server_ve
 (1 row)
 
 -- json output
-select pgsp_format_json();
- pgsp_format_json 
-------------------
- 
-(1 row)
-
+set pg_show_plans.plan_format = 'json';
 show pg_show_plans.plan_format;
  pg_show_plans.plan_format 
 ---------------------------
@@ -51,12 +46,7 @@ select * from nest();
 (2 rows)
 
 -- yaml output
-select pgsp_format_yaml();
- pgsp_format_yaml 
-------------------
- 
-(1 row)
-
+set pg_show_plans.plan_format = 'yaml';
 show pg_show_plans.plan_format;
  pg_show_plans.plan_format 
 ---------------------------
@@ -90,12 +80,7 @@ select * from nest();
 (2 rows)
 
 -- xml output
-select pgsp_format_xml();
- pgsp_format_xml 
------------------
- 
-(1 row)
-
+set pg_show_plans.plan_format = 'xml';
 show pg_show_plans.plan_format;
  pg_show_plans.plan_format 
 ---------------------------

expected/formats_1.out

@@ -22,6 +22,7 @@ as $$
   end;
 $$;
 -- text output
+set pg_show_plans.plan_format = 'text';
 show pg_show_plans.plan_format;
  pg_show_plans.plan_format 
 ---------------------------
@@ -42,5 +43,3 @@ select * from nest();
        |   Filter: (level >= 0)
 (2 rows)
 
-set pg_show_plans.plan_format = 'json'; -- fails
-ERROR:  parameter "pg_show_plans.plan_format" cannot be changed without restarting the server

expected/pg_show_plans.out

@@ -0,0 +1,4 @@
+DROP FUNCTION gsp_format_text;
+DROP FUNCTION gsp_format_json;
+DROP FUNCTION gsp_format_yaml;
+DROP FUNCTION gsp_format_xml;

pg_show_plans--1.1--2.0.sql

@@ -0,0 +1,36 @@
+/* pg_show_plans/pg_show_plans--2.0.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION pg_show_plans" to load this file. \quit
+
+-- Register functions.
+CREATE FUNCTION pg_show_plans_enable()
+RETURNS void
+AS 'MODULE_PATHNAME'
+LANGUAGE C;
+
+CREATE FUNCTION pg_show_plans_disable()
+RETURNS void
+AS 'MODULE_PATHNAME'
+LANGUAGE C;
+
+CREATE FUNCTION pg_show_plans(
+	OUT pid int,
+	OUT level int,
+	OUT userid oid,
+	OUT dbid oid,
+	OUT plan text
+)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME'
+LANGUAGE C;
+
+-- Register a view on the function for ease of use.
+CREATE VIEW pg_show_plans AS
+	SELECT * FROM pg_show_plans();
+
+GRANT SELECT ON pg_show_plans TO PUBLIC;
+
+-- Don't want this to be available to non-superusers.
+REVOKE ALL ON FUNCTION pg_show_plans_enable() FROM PUBLIC;
+REVOKE ALL ON FUNCTION pg_show_plans_disable() FROM PUBLIC;

pg_show_plans--2.0.sql

@@ -89,6 +89,8 @@ static void set_state(const bool state);
 static const char *show_state(void);
 /* Set query plan output format: text, json, ... */
 static void set_format(const int format);
+/* Propagate GUC variable value to shared memory (assign hook). */
+static void prop_format_to_shmem(int newval, void *extra);
 static const char *show_format(void);
 /* Check the extension has been properly loaded. */
 static inline void shmem_safety_check(void);
@@ -109,11 +111,6 @@ static void pgsp_ExecutorRun(QueryDesc *queryDesc, ScanDirection direction,
 /* Enables/Disables the extension. */
 Datum pg_show_plans_enable(PG_FUNCTION_ARGS);
 Datum pg_show_plans_disable(PG_FUNCTION_ARGS);
-/* Sets query plan output format. */
-Datum pgsp_format_text(PG_FUNCTION_ARGS);
-Datum pgsp_format_json(PG_FUNCTION_ARGS);
-Datum pgsp_format_yaml(PG_FUNCTION_ARGS);
-Datum pgsp_format_xml(PG_FUNCTION_ARGS);
 /* Show query plans of all the currently running statements. */
 Datum pg_show_plans(PG_FUNCTION_ARGS);
 
@@ -195,9 +192,9 @@ _PG_init(void)
 	                         &plan_format,
 	                         EXPLAIN_FORMAT_TEXT,
 	                         plan_formats,
-	                         PGC_POSTMASTER,
+	                         PGC_USERSET,
 	                         0,
-	                         NULL, NULL, show_format);
+	                         NULL, prop_format_to_shmem, show_format);
 
 	/* Save old hooks, and install new ones. */
 #if PG_VERSION_NUM >= 150000
@@ -346,11 +343,21 @@ show_state()
 static void
 set_format(const int format)
 {
-	shmem_safety_check();
-	if (is_allowed_role())
+	/* Shared memory may not be fully available at server start, so we do not
+	 * check for pgsp_hash availability here. That is why the following line is
+	 * commented out. */
+	/* shmem_safety_check(); */
+
+	if (pgsp != NULL && is_allowed_role())
 		pgsp->plan_format = format;
 }
 
+static void
+prop_format_to_shmem(int newval, void *extra)
+{
+	set_format(newval);
+}
+
 static const char *
 show_format()
 {
@@ -521,34 +528,6 @@ pg_show_plans_disable(PG_FUNCTION_ARGS)
 	PG_RETURN_VOID();
 }
 
-Datum
-pgsp_format_text(PG_FUNCTION_ARGS)
-{
-	set_format(EXPLAIN_FORMAT_TEXT);
-	PG_RETURN_VOID();
-}
-
-Datum
-pgsp_format_json(PG_FUNCTION_ARGS)
-{
-	set_format(EXPLAIN_FORMAT_JSON);
-	PG_RETURN_VOID();
-}
-
-Datum
-pgsp_format_yaml(PG_FUNCTION_ARGS)
-{
-	set_format(EXPLAIN_FORMAT_YAML);
-	PG_RETURN_VOID();
-}
-
-Datum
-pgsp_format_xml(PG_FUNCTION_ARGS)
-{
-	set_format(EXPLAIN_FORMAT_XML);
-	PG_RETURN_VOID();
-}
-
 Datum
 pg_show_plans(PG_FUNCTION_ARGS)
 {

pg_show_plans.c

@@ -1,5 +1,5 @@
 # pg_show_plans extension
 comment = 'show query plans of all currently running SQL statements'
-default_version = '1.1'
+default_version = '2.0'
 module_pathname = '$libdir/pg_show_plans'
 relocatable = true

pg_show_plans.control

@@ -2,17 +2,17 @@
 select setting::int < 140000 as pg12_13 from pg_settings where name = 'server_version_num';
 
 -- json output
-select pgsp_format_json();
+set pg_show_plans.plan_format = 'json';
 show pg_show_plans.plan_format;
 select * from nest();
 
 -- yaml output
-select pgsp_format_yaml();
+set pg_show_plans.plan_format = 'yaml';
 show pg_show_plans.plan_format;
 select * from nest();
 
 -- xml output
-select pgsp_format_xml();
+set pg_show_plans.plan_format = 'xml';
 show pg_show_plans.plan_format;
 select * from nest();