Clean up description of 9.0's incompatible changes in SIMILAR TO and

SQL-style substring().

diff --git a/doc/src/sgml/release-9.0.sgml b/doc/src/sgml/release-9.0.sgml
index 70d9822450fdaf01268231fad3119380a52611c9..bd1b1e7e104d38852253988ee9965de292ff5486 100644 (file)
--- a/doc/src/sgml/release-9.0.sgml
+++ b/doc/src/sgml/release-9.0.sgml
@@ -1,4 +1,4 @@
-
+
 
 
  
@@ -50,7 +50,7 @@
             defaulted to off for many years (Tom Lane)
           
         
-  
+
         
           
             Remove server variable regex_flavor, which
@@ -59,9 +59,9 @@
             (e.g. Perl-regex compatible) for many years (Tom Lane)
           
         
-      
+
       
-      
+
     
 
     
@@ -97,43 +97,30 @@
 
       
         
-          Fix SIMILAR
-          TO to match the SQL standard-specified behavior
-          by processing ? and {} the same way
-          they are processed in regular expressions (Tom Lane)
-        
-      
-
-      
-        
-          Properly treat ^ and $ as literals in
-          SIMILAR TO patterns, to match the SQL standard (Tom Lane)
-        
-
-        
-          Previously these were treated using regular expression syntax.  This
-          change breaks backward compatibility.  This also affects
-          substring()'s interpretation of regular expressions.
-        
-      
-
-      
-        
-          Process parentheses as literals in SIMILAR TO expressions;
-          also make character class handling more standards-compliant (Tom Lane)
+          Improve standards compliance of 
+          linkend="functions-similarto-regexp">SIMILAR TO
+          patterns and SQL-style substring() patterns (Tom Lane)
         
 
         
-          This also affects substring()'s handling of regular
-          expressions.
+          This includes treating ? and {...} as
+          pattern metacharacters, while they were simple literal characters
+          before; that corresponds to new features added in SQL:2008.
+          Also, ^ and $ are now treated as simple
+          literal characters; formerly they were treated as metacharacters,
+          as if the pattern were following POSIX rather than SQL rules.
+          Also, in SQL-standard substring(), use of parentheses
+          for nesting no longer interferes with capturing of a substring.
+          Also, processing of bracket expressions (character classes) is
+          now more standards-compliant.
         
       
 
       
         
-          Do not allow 
-          linkend="functions-string-sql">substring()
-          to have a negative third length, per the SQL standard (Tom Lane)
+         Reject negative length values in 3-parameter 
+         linkend="functions-string-sql">substring()
+         for bit strings, per the SQL standard (Tom Lane)
         
       
 
@@ -1392,7 +1379,7 @@
 
           
             
-              Install server-side language PL/pgSQL by default (Bruce Momjian) 
+              Install server-side language PL/pgSQL by default (Bruce Momjian)
             
           
 




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