fix #232 add if clause for sql server

Author: mightymop

src/java/org/jivesoftware/openfire/archive/ArchiveSearcher.java

@@ -351,6 +351,11 @@ private Collection<Conversation> databaseSearch(ArchiveSearch search) {
             // rows we need returned. The syntax is LIMIT [rows] OFFSET [offset]
             else if (DbConnectionManager.getDatabaseType() == DbConnectionManager.DatabaseType.postgresql) {
                 query.append(" LIMIT ").append(numResults).append(" OFFSET ").append(startIndex);
+            }
+			// SQL Server optimization: use the OFFSET command to tell the database how many
+            // rows we need returned. The syntax is OFFSET [offset] FETCH NEXT [rows] ROWS ONLY
+			else if (DbConnectionManager.getDatabaseType() == DbConnectionManager.DatabaseType.sqlserver) {
+                query.append(" OFFSET ").append(startIndex).append(" ROWS FETCH NEXT ").append(numResults).append(" ROWS ONLY ");
             }
         }