v2-0001-Expose-GUC-flags-in-SQL-function-replacing-check_.patch

From a87afcfb5757367aeef795505e9361d5a03facc7 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Sat, 29 Jan 2022 15:32:10 +0900
Subject: [PATCH v2] Expose GUC flags in SQL function, replacing check_guc

Note-to-self: CATVERSION bump!
---
 src/include/catalog/pg_proc.dat   |  6 +++
 src/backend/utils/misc/check_guc  | 78 -------------------------------
 src/backend/utils/misc/guc.c      | 39 ++++++++++++++++
 src/test/regress/expected/guc.out | 71 ++++++++++++++++++++++++++++
 src/test/regress/sql/guc.sql      | 41 ++++++++++++++++
 doc/src/sgml/func.sgml            | 39 ++++++++++++++++
 6 files changed, 196 insertions(+), 78 deletions(-)
 delete mode 100755 src/backend/utils/misc/check_guc

diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 0859dc81ca..3f927acb01 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6096,6 +6096,12 @@
   proargmodes => '{o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
   proargnames => '{name,setting,unit,category,short_desc,extra_desc,context,vartype,source,min_val,max_val,enumvals,boot_val,reset_val,sourcefile,sourceline,pending_restart}',
   prosrc => 'show_all_settings' },
+
+{ oid => '8921', descr => 'return flags for specified GUC',
+  proname => 'pg_settings_get_flags', provolatile => 's',
+  prorettype => '_text', proargtypes => 'text',
+  prosrc => 'pg_settings_get_flags' },
+
 { oid => '3329', descr => 'show config file settings',
   proname => 'pg_show_all_file_settings', prorows => '1000', proretset => 't',
   provolatile => 'v', prorettype => 'record', proargtypes => '',
diff --git a/src/backend/utils/misc/check_guc b/src/backend/utils/misc/check_guc
deleted file mode 100755
index b171ef0e4f..0000000000
--- a/src/backend/utils/misc/check_guc
+++ /dev/null
@@ -1,78 +0,0 @@
-#!/bin/sh
-
-## currently, this script makes a lot of assumptions:
-## in postgresql.conf.sample:
-##   1) the valid config settings may be preceded by a '#', but NOT '# '
-##      (we use this to skip comments)
-##   2) the valid config settings will be followed immediately by  ' ='
-##      (at least one space preceding the '=')
-## in guc.c:
-##   3) the options have PGC_ on the same line as the option
-##   4) the options have '{' on the same line as the option
-
-##  Problems
-## 1) Don't know what to do with TRANSACTION ISOLATION LEVEL
-
-## if an option is valid but shows up in only one file (guc.c but not
-## postgresql.conf.sample), it should be listed here so that it
-## can be ignored
-INTENTIONALLY_NOT_INCLUDED="debug_deadlocks in_hot_standby \
-is_superuser lc_collate lc_ctype lc_messages lc_monetary lc_numeric lc_time \
-pre_auth_delay role seed server_encoding server_version server_version_num \
-session_authorization trace_lock_oidmin trace_lock_table trace_locks trace_lwlocks \
-trace_notify trace_userlocks transaction_isolation transaction_read_only \
-zero_damaged_pages"
-
-### What options are listed in postgresql.conf.sample, but don't appear
-### in guc.c?
-
-# grab everything that looks like a setting and convert it to lower case
-SETTINGS=`grep ' =' postgresql.conf.sample |
-grep -v '^# ' | # strip comments
-sed -e 's/^#//' |
-awk '{print $1}'`
-
-SETTINGS=`echo "$SETTINGS" | tr 'A-Z' 'a-z'`
-
-for i in $SETTINGS ; do
-  hidden=0
-  ## it sure would be nice to replace this with an sql "not in" statement
-  ## it doesn't seem to make sense to have things in .sample and not in guc.c
-#  for hidethis in $INTENTIONALLY_NOT_INCLUDED ; do
-#    if [ "$hidethis" = "$i" ] ; then
-#      hidden=1
-#    fi
-#  done
-  if [ "$hidden" -eq 0 ] ; then
-    grep -i '"'$i'"' guc.c > /dev/null
-    if [ $? -ne 0 ] ; then
-      echo "$i seems to be missing from guc.c";
-    fi;
-  fi
-done
-
-### What options are listed in guc.c, but don't appear
-### in postgresql.conf.sample?
-
-# grab everything that looks like a setting and convert it to lower case
-
-SETTINGS=`grep '{.* PGC_' guc.c | awk '{print $1}' | \
-          sed -e 's/{//g' -e 's/"//g' -e 's/,//'`
-
-SETTINGS=`echo "$SETTINGS" | tr 'A-Z' 'a-z'`
-
-for i in $SETTINGS ; do
-  hidden=0
-  ## it sure would be nice to replace this with an sql "not in" statement
-  for hidethis in $INTENTIONALLY_NOT_INCLUDED ; do
-    if [ "$hidethis" = "$i" ] ; then
-      hidden=1
-    fi
-  done
-  if [ "$hidden" -eq 0 ] ; then
-    grep -i '#'$i' ' postgresql.conf.sample > /dev/null
-    if [ $? -ne 0 ] ; then
-      echo "$i seems to be missing from postgresql.conf.sample";
-    fi
-  fi
-done
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 4c94f09c64..b3fd42e0f1 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -9634,6 +9634,45 @@ GetConfigOptionByName(const char *name, const char **varname, bool missing_ok)
 	return _ShowOption(record, true);
 }
 
+/*
+ * Return some of the flags associated to the specified GUC in the shape of
+ * a text array, and NULL if it does not exist.  An empty array is returned
+ * if the GUC exists without any meaningful flags to show.
+ */
+Datum
+pg_settings_get_flags(PG_FUNCTION_ARGS)
+{
+#define MAX_GUC_FLAGS	5
+	char	   *varname = TextDatumGetCString(PG_GETARG_DATUM(0));
+	struct config_generic *record;
+	int			cnt = 0;
+	Datum		flags[MAX_GUC_FLAGS];
+	ArrayType  *a;
+
+	record = find_option(varname, false, true, ERROR);
+
+	/* return NULL if no such variable */
+	if (record == NULL)
+		PG_RETURN_NULL();
+
+	if (record->flags & GUC_EXPLAIN)
+		flags[cnt++] = CStringGetTextDatum("EXPLAIN");
+	if (record->flags & GUC_NO_RESET_ALL)
+		flags[cnt++] = CStringGetTextDatum("NO_RESET_ALL");
+	if (record->flags & GUC_NO_SHOW_ALL)
+		flags[cnt++] = CStringGetTextDatum("NO_SHOW_ALL");
+	if (record->flags & GUC_NOT_IN_SAMPLE)
+		flags[cnt++] = CStringGetTextDatum("NOT_IN_SAMPLE");
+	if (record->flags & GUC_RUNTIME_COMPUTED)
+		flags[cnt++] = CStringGetTextDatum("RUNTIME_COMPUTED");
+
+	Assert(cnt <= MAX_GUC_FLAGS);
+
+	/* Returns the record as Datum */
+	a = construct_array(flags, cnt, TEXTOID, -1, false, TYPALIGN_INT);
+	PG_RETURN_ARRAYTYPE_P(a);
+}
+
 /*
  * Return GUC variable value by variable number; optionally return canonical
  * form of name.  Return value is palloc'd.
diff --git a/src/test/regress/expected/guc.out b/src/test/regress/expected/guc.out
index 59da91ff04..5fe53c82e3 100644
--- a/src/test/regress/expected/guc.out
+++ b/src/test/regress/expected/guc.out
@@ -813,3 +813,74 @@ set default_with_oids to f;
 -- Should not allow to set it to true.
 set default_with_oids to t;
 ERROR:  tables declared WITH OIDS are not supported
+-- Test GUC categories and flag patterns
+CREATE TABLE pg_settings_flags AS SELECT name, category,
+    'EXPLAIN'          = ANY(flags) AS explain,
+    'NO_RESET_ALL'     = ANY(flags) AS no_reset_all,
+    'NO_SHOW_ALL'      = ANY(flags) AS no_show_all,
+    'NOT_IN_SAMPLE'    = ANY(flags) AS not_in_sample,
+    'RUNTIME_COMPUTED' = ANY(flags) AS runtime_computed
+  FROM pg_show_all_settings() AS psas,
+    pg_settings_get_flags(psas.name) AS flags;
+-- Developer GUCs should be flagged with GUC_NOT_IN_SAMPLE:
+SELECT name FROM pg_settings_flags
+  WHERE category = 'Developer Options' AND NOT not_in_sample
+  ORDER BY 1;
+ name 
+------
+(0 rows)
+
+-- Most query-tuning GUCs are flagged as valid for EXPLAIN.
+-- default_statistics_target is an exception.
+SELECT name FROM pg_settings_flags
+  WHERE category ~ '^Query Tuning' AND NOT explain
+  ORDER BY 1;
+           name            
+---------------------------
+ default_statistics_target
+(1 row)
+
+-- Runtime-computed GUCs should be part of the preset category.
+SELECT name FROM pg_settings_flags
+  WHERE NOT category = 'Preset Options' AND runtime_computed
+  ORDER BY 1;
+ name 
+------
+(0 rows)
+
+-- Preset GUCs are flagged as NOT_IN_SAMPLE.
+SELECT name FROM pg_settings_flags
+  WHERE category = 'Preset Options' AND NOT not_in_sample
+  ORDER BY 1;
+ name 
+------
+(0 rows)
+
+-- NO_SHOW_ALL implies NO_RESET_ALL, and vice-versa.
+SELECT name FROM pg_settings_flags
+  WHERE no_show_all AND NOT no_reset_all
+  ORDER BY 1;
+ name 
+------
+(0 rows)
+
+-- Three exceptions as of transaction_*
+SELECT name FROM pg_settings_flags
+  WHERE NOT no_show_all AND no_reset_all
+  ORDER BY 1;
+          name          
+------------------------
+ transaction_deferrable
+ transaction_isolation
+ transaction_read_only
+(3 rows)
+
+-- NO_SHOW_ALL implies NOT_IN_SAMPLE:
+SELECT name FROM pg_settings_flags
+  WHERE no_show_all AND NOT not_in_sample
+  ORDER BY 1;
+ name 
+------
+(0 rows)
+
+DROP TABLE pg_settings_flags;
diff --git a/src/test/regress/sql/guc.sql b/src/test/regress/sql/guc.sql
index c39c11388d..7a78b8f3be 100644
--- a/src/test/regress/sql/guc.sql
+++ b/src/test/regress/sql/guc.sql
@@ -311,3 +311,44 @@ reset check_function_bodies;
 set default_with_oids to f;
 -- Should not allow to set it to true.
 set default_with_oids to t;
+
+-- Test GUC categories and flag patterns
+CREATE TABLE pg_settings_flags AS SELECT name, category,
+    'EXPLAIN'          = ANY(flags) AS explain,
+    'NO_RESET_ALL'     = ANY(flags) AS no_reset_all,
+    'NO_SHOW_ALL'      = ANY(flags) AS no_show_all,
+    'NOT_IN_SAMPLE'    = ANY(flags) AS not_in_sample,
+    'RUNTIME_COMPUTED' = ANY(flags) AS runtime_computed
+  FROM pg_show_all_settings() AS psas,
+    pg_settings_get_flags(psas.name) AS flags;
+
+-- Developer GUCs should be flagged with GUC_NOT_IN_SAMPLE:
+SELECT name FROM pg_settings_flags
+  WHERE category = 'Developer Options' AND NOT not_in_sample
+  ORDER BY 1;
+-- Most query-tuning GUCs are flagged as valid for EXPLAIN.
+-- default_statistics_target is an exception.
+SELECT name FROM pg_settings_flags
+  WHERE category ~ '^Query Tuning' AND NOT explain
+  ORDER BY 1;
+-- Runtime-computed GUCs should be part of the preset category.
+SELECT name FROM pg_settings_flags
+  WHERE NOT category = 'Preset Options' AND runtime_computed
+  ORDER BY 1;
+-- Preset GUCs are flagged as NOT_IN_SAMPLE.
+SELECT name FROM pg_settings_flags
+  WHERE category = 'Preset Options' AND NOT not_in_sample
+  ORDER BY 1;
+-- NO_SHOW_ALL implies NO_RESET_ALL, and vice-versa.
+SELECT name FROM pg_settings_flags
+  WHERE no_show_all AND NOT no_reset_all
+  ORDER BY 1;
+-- Three exceptions as of transaction_*
+SELECT name FROM pg_settings_flags
+  WHERE NOT no_show_all AND no_reset_all
+  ORDER BY 1;
+-- NO_SHOW_ALL implies NOT_IN_SAMPLE:
+SELECT name FROM pg_settings_flags
+  WHERE no_show_all AND NOT not_in_sample
+  ORDER BY 1;
+DROP TABLE pg_settings_flags;
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 0ee6974f1c..0cf1ffbcb0 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -23596,6 +23596,45 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
        </para></entry>
       </row>
 
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_get_get_flags</primary>
+        </indexterm>
+        <function>pg_get_get_flags</function> ( <parameter>guc</parameter> <type>text</type> )
+        <returnvalue>text[]</returnvalue>
+       </para>
+       <para>
+        Returns an array of the flags associated with the given GUC, or
+        <literal>NULL</literal> if the  does not exist.  The result is
+        an empty array if the GUC exists but there are no flags to show,
+        as supported by the list below.
+        The following flags are exposed (the most meaningful ones are
+        included):
+        <simplelist>
+         <member>
+          <literal>EXPLAIN</literal>, parameters included in
+          <command>EXPLAIN</command> commands.
+         </member>
+         <member>
+          <literal>NO_SHOW_ALL</literal>, parameters excluded from
+          <command>SHOW ALL</command> commands.
+         </member>
+         <member>
+          <literal>NO_RESET_ALL</literal>, parameters excluded from
+          <command>RESET ALL</command> commands.
+         </member>
+         <member>
+          <literal>NOT_IN_SAMPLE</literal>, parameters not included in
+          <filename>postgresql.conf</filename> by default.
+         </member>
+         <member>
+          <literal>RUNTIME_COMPUTED</literal>, runtime-computed parameters.
+         </member>
+        </simplelist>
+       </para></entry>
+      </row>
+
       <row>
        <entry role="func_table_entry"><para role="func_signature">
         <indexterm>
-- 
2.34.1