Change the default value of standard_conforming_strings to on.

This change should be publicized to driver maintainers at once and
release-noted as an incompatibility with previous releases.

doc/src/sgml/config.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.296 2010/07/16 22:25:47 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.297 2010/07/20 00:34:44 rhaas Exp $ -->
 
 <chapter Id="runtime-config">
   <title>Server Configuration</title>
@@ -5237,11 +5237,8 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir'
         This controls whether ordinary string literals
         (<literal>'...'</>) treat backslashes literally, as specified in
         the SQL standard.
-        The default is currently <literal>off</>, causing
-        <productname>PostgreSQL</productname> to have its historical
-        behavior of treating backslashes as escape characters.
-        The default will change to <literal>on</> in a future release
-        to improve compatibility with the SQL standard.
+        Beginning in <productname>PostgreSQL</productname> 9.1, the default is
+        <literal>on</> (prior releases defaulted to <literal>off</>).
         Applications can check this
         parameter to determine how string literals will be processed.
         The presence of this parameter can also be taken as an indication

doc/src/sgml/syntax.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/syntax.sgml,v 1.147 2010/07/03 02:57:46 rhaas Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/syntax.sgml,v 1.148 2010/07/20 00:34:44 rhaas Exp $ -->
 
 <chapter id="sql-syntax">
  <title>SQL Syntax</title>
@@ -445,16 +445,15 @@ SELECT 'foo'      'bar';
      If the configuration parameter
      <xref linkend="guc-standard-conforming-strings"> is <literal>off</>,
      then <productname>PostgreSQL</productname> recognizes backslash escapes
-     in both regular and escape string constants.  This is for backward
-     compatibility with the historical behavior, where backslash escapes
-     were always recognized.
-     Although <varname>standard_conforming_strings</> currently defaults to
-     <literal>off</>, the default will change to <literal>on</> in a future
-     release for improved standards compliance.  Applications are therefore
-     encouraged to migrate away from using backslash escapes.  If you need
-     to use a backslash escape to represent a special character, write the
-     string constant with an <literal>E</> to be sure it will be handled the same
-     way in future releases.
+     in both regular and escape string constants.  However, as of
+     <productname>PostgreSQL</> 9.1, the default is <literal>on</>, meaning
+     that backslash escapes are recognized only in escape string constants.
+     This behavior is more standards-compliant, but might break applications
+     which rely on the historical behavior, where backslash escapes
+     were always recognized.  As a workaround, you can set this parameter
+     to <literal>off</>, but it is better to migrate away from using backslash
+     escapes.  If you need to use a backslash escape to represent a special
+     character, write the string constant with an <literal>E</>.
     </para>
 
     <para>

src/backend/parser/scan.l

@@ -24,7 +24,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/scan.l,v 1.167 2010/05/30 18:10:41 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/scan.l,v 1.168 2010/07/20 00:34:44 rhaas Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -52,7 +52,7 @@
  */
 int				backslash_quote = BACKSLASH_QUOTE_SAFE_ENCODING;
 bool			escape_string_warning = true;
-bool			standard_conforming_strings = false;
+bool			standard_conforming_strings = true;
 
 /*
  * Set the type of YYSTYPE.

src/backend/utils/misc/guc.c

@@ -10,7 +10,7 @@
  * Written by Peter Eisentraut <peter_e@gmx.net>.
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.562 2010/07/16 22:25:50 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.563 2010/07/20 00:34:44 rhaas Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -1211,7 +1211,7 @@ static struct config_bool ConfigureNamesBool[] =
 			GUC_REPORT
 		},
 		&standard_conforming_strings,
-		false, NULL, NULL
+		true, NULL, NULL
 	},
 
 	{

src/backend/utils/misc/postgresql.conf.sample

@@ -511,7 +511,7 @@
 #escape_string_warning = on
 #lo_compat_privileges = off
 #sql_inheritance = on
-#standard_conforming_strings = off
+#standard_conforming_strings = on
 #synchronize_seqscans = on
 
 # - Other Platforms and Clients -