As discussed on several occasions previously, the new anonymous

composite type capability makes it possible to create a system view
based on a table function in a way that is hopefully palatable to
everyone. The attached patch takes advantage of this, moving
show_all_settings() from contrib/tablefunc into the backend (renamed
all_settings(). It is defined as a builtin returning type RECORD. During
initdb a system view is created to expose the same information presently
available through SHOW ALL. For example:

test=# select * from pg_settings where name like '%debug%';
          name          | setting
-----------------------+---------
  debug_assertions      | on
  debug_pretty_print    | off
  debug_print_parse     | off
  debug_print_plan      | off
  debug_print_query     | off
  debug_print_rewritten | off
  wal_debug             | 0
(7 rows)


Additionally during initdb two rules are created which make it possible
to change settings by updating the system view -- a "virtual table" as
Tom put it. Here's an example:

Joe Conway

1 files changed, 16 insertions, 1 deletions

diff --git a/src/bin/initdb/initdb.sh b/src/bin/initdb/initdb.sh
index 0a09d6252f2..d876a888a20 100644
--- a/src/bin/initdb/initdb.sh
+++ b/src/bin/initdb/initdb.sh
@@ -27,7 +27,7 @@
 # Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
 # Portions Copyright (c) 1994, Regents of the University of California
 #
-# $Header: /cvsroot/pgsql/src/bin/initdb/Attic/initdb.sh,v 1.165 2002/08/08 19:39:05 tgl Exp $
+# $Header: /cvsroot/pgsql/src/bin/initdb/Attic/initdb.sh,v 1.166 2002/08/15 02:51:26 momjian Exp $
 #
 #-------------------------------------------------------------------------
 
@@ -1015,6 +1015,21 @@ CREATE VIEW pg_stat_database AS \
             pg_stat_get_db_blocks_hit(D.oid) AS blks_hit \
     FROM pg_database D;
 
+CREATE VIEW pg_settings AS \
+    SELECT \
+            A.name, \
+            A.setting \
+    FROM pg_show_all_settings() AS A(name text, setting text);
+
+CREATE RULE pg_settings_u AS \
+    ON UPDATE TO pg_settings \
+    WHERE new.name = old.name DO \
+    SELECT set_config(old.name, new.setting, 'f');
+
+CREATE RULE pg_settings_n AS \
+    ON UPDATE TO pg_settings \
+    DO INSTEAD NOTHING;
+
 EOF
 if [ "$?" -ne 0 ]; then
     exit_nicely