In HA/load balancing does:

Clarify sync/async replication propogation delay issues.
Add SGML comment about Oracle RAC and remove doc mention.
Add item about Multi-master replication with conflict resolution.

diff --git a/doc/src/sgml/high-availability.sgml b/doc/src/sgml/high-availability.sgml
index 185b77b04c7b731da4ee37b66df17fc86e69283a..d3ef45944f7e5638308689dd16c81364227f6803 100644 (file)
--- a/doc/src/sgml/high-availability.sgml
+++ b/doc/src/sgml/high-availability.sgml
@@ -1,4 +1,4 @@
-
+
 
 
  High Availability and Load Balancing
@@ -45,16 +45,17 @@
  
 
  
-  Some failover and load balancing solutions are synchronous, meaning that
-  a data-modifying transaction is not considered committed until all
-  servers have committed the transaction.  This guarantees that a failover
-  will not lose any data and that all load-balanced servers will return
-  consistent results with no propagation delay. Asynchronous updating has
-  a small delay between the time of commit and its propagation to the
-  other servers, opening the possibility that some transactions might be
-  lost in the switch to a backup server, and that load balanced servers
-  might return slightly stale results.  Asynchronous communication is used
-  when synchronous would be too slow.
+  Some failover and load balancing solutions are synchronous,
+  meaning that a data-modifying transaction is not considered
+  committed until all servers have committed the transaction.  This
+  guarantees that a failover will not lose any data and that all
+  load-balanced servers will return consistent results with little
+  propagation delay. Asynchronous updating has a delay between the
+  time of commit and its propagation to the other servers, opening
+  the possibility that some transactions might be lost in the switch
+  to a backup server, and that load balanced servers might return
+  slightly stale results.  Asynchronous communication is used when
+  synchronous would be too slow.
  
 
  
@@ -103,6 +104,16 @@
     current, but the mirroring must be done in a way that the
     standby server has a consistent copy of the file system.
    
+
+
+
   
  
 
@@ -173,7 +184,7 @@
  
 
  
-  Multi-Master Replication Using Clustering
+  Multi-Master Clustering
   
 
    
@@ -192,11 +203,9 @@
    
 
    
-    Clustering is implemented by Oracle in their
-    RAC product.  PostgreSQL
-    does not offer this type of load balancing, though
-    PostgreSQL two-phase commit (
-    linkend="sql-prepare-transaction"
+    PostgreSQL does not offer this type of load
+    balancing, though PostgreSQL two-phase commit
+    (
     endterm="sql-prepare-transaction-title"> and 
     linkend="sql-commit-prepared" endterm="sql-commit-prepared-title">)
     can be used to implement this in application code or middleware.
@@ -204,6 +213,20 @@
   
  
 
+ 
+  Multi-Master With Conflict Resolution
+  
+
+   
+    For servers that are not regularly connected, like laptops or
+    remote servers, keeping data consistent among servers is a
+    challenge.  One simple solution is to allow each server to
+    modify the data, and have periodic communication compare
+    databases and ask users to resolve any conflicts.
+   
+  
+ 
+
  
   Data Partitioning
   




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