Starting with Oracle 11g R2 (RAC), the behavior of the CREATE TABLE statement has changed, when creating a conventional table in a database created with the default options then the initial segment is not created until the first row is inserted into the table. see http://download.oracle.com/docs/cd/E11882_01/server.112/e10595/tables002.htm#ADMIN13319 for more details. We found a potential downside to this change : The sequences created as default ( start with 1 increment by 1) are not staring with "1" when used in insert query script, Instead they are starting with 2 or 4, this can not be changed even explicitly tell Oracle that the first value is "1". In another words, when using Hibernate with Oracle 11g R2 (RAC), if the ID generator class is "sequence-identity", the first value is NOT 1. Two ways to work around this issue: 1. Using another ID generator class. 2. Disable deferred segment creation of Oracle by setting the initialization parameter DEFERRED_SEGMENT_CREATION to FALSE. The new clauses SEGMENT CREATION DEFERRED and SEGMENT CREATION IMMEDIATE are available for the CREATE TABLE statement. These clauses override the setting of the DEFERRED_SEGMENT_CREATION initialization parameter.

In Oracle 11g R2 (both RAC and standalone), a sequence may start at 2 instead of 1. The root cause is still under analysis. There are currently two workarounds for this issue:      <orderedlist>     <listitem>       <para>Use another ID generator class.</para>     </listitem>     <listitem>       <para>Disable deferred segment creation of Oracle by setting the initialization parameter <parameter>DEFERRED_SEGMENT_CREATION       </parameter> to <literal>FALSE</literal>. The new clauses <parameter>SEGMENT CREATION DEFERRED</parameter> and <parameter>SEGMENT       CREATION IMMEDIATE</parameter> are available for the <parameter>CREATE TABLE</parameter> statement. These clauses override the       setting of the <parameter>DEFERRED_SEGMENT_CREATION</parameter> initialization parameter.</para>     </listitem>   </orderedlist>