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ImplicitTransactionManagementPolicy
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com.google.appengine.api.datastore</FONT>
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Enum ImplicitTransactionManagementPolicy</H2>
<PRE>
java.lang.Object
  <IMG SRC="../../../../../resources/inherit.gif" ALT="extended by ">java.lang.Enum&lt;<A HREF="../../../../../com/google/appengine/api/datastore/ImplicitTransactionManagementPolicy.html" title="enum in com.google.appengine.api.datastore">ImplicitTransactionManagementPolicy</A>&gt;
      <IMG SRC="../../../../../resources/inherit.gif" ALT="extended by "><B>com.google.appengine.api.datastore.ImplicitTransactionManagementPolicy</B>
</PRE>
<DL>
<DT><B>All Implemented Interfaces:</B> <DD>java.io.Serializable, java.lang.Comparable&lt;<A HREF="../../../../../com/google/appengine/api/datastore/ImplicitTransactionManagementPolicy.html" title="enum in com.google.appengine.api.datastore">ImplicitTransactionManagementPolicy</A>&gt;</DD>
</DL>
<HR>
<DL>
<DT><PRE>public enum <B>ImplicitTransactionManagementPolicy</B><DT>extends java.lang.Enum&lt;<A HREF="../../../../../com/google/appengine/api/datastore/ImplicitTransactionManagementPolicy.html" title="enum in com.google.appengine.api.datastore">ImplicitTransactionManagementPolicy</A>&gt;</DL>
</PRE>

<P>
Describes the various policies the datastore can follow for implicit
 transaction management.  When deciding which policy to use, keep the
 following in mind: The datastore will automatically retry operations
 that fail due to concurrent updates to the same entity group if the
 operation is not part of a transaction.  The datastore will not retry
 operations that fail due to concurrent updates to the same entity group
 if the operation is part of a transaction, and will instead immediately
 throw a <CODE>ConcurrentModificationException</CODE>.  If your application
 needs to perform any sort of intelligent merging when concurrent attempts
 are made to update the same entity group you probably want <A HREF="../../../../../com/google/appengine/api/datastore/ImplicitTransactionManagementPolicy.html#AUTO"><CODE>AUTO</CODE></A>,
 otherwise <A HREF="../../../../../com/google/appengine/api/datastore/ImplicitTransactionManagementPolicy.html#NONE"><CODE>NONE</CODE></A> is probably acceptable.

 See <A HREF="../../../../../com/google/appengine/api/datastore/DatastoreService.html" title="interface in com.google.appengine.api.datastore"><CODE>DatastoreService</CODE></A> for a list of operations that perform implicit
 transaction management.
<P>

<P>
<HR>

<P>
<!-- =========== ENUM CONSTANT SUMMARY =========== -->

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<TR BGCOLOR="white" CLASS="TableRowColor">
<TD><CODE><B><A HREF="../../../../../com/google/appengine/api/datastore/ImplicitTransactionManagementPolicy.html#AUTO">AUTO</A></B></CODE>

<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;If a current transaction exists, use it, otherwise create one.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD><CODE><B><A HREF="../../../../../com/google/appengine/api/datastore/ImplicitTransactionManagementPolicy.html#NONE">NONE</A></B></CODE>

<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;If a current transaction exists, use it, otherwise execute without a
 transaction.</TD>
</TR>
</TABLE>
&nbsp;
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<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>static&nbsp;<A HREF="../../../../../com/google/appengine/api/datastore/ImplicitTransactionManagementPolicy.html" title="enum in com.google.appengine.api.datastore">ImplicitTransactionManagementPolicy</A></CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../../../com/google/appengine/api/datastore/ImplicitTransactionManagementPolicy.html#valueOf(java.lang.String)">valueOf</A></B>(java.lang.String&nbsp;name)</CODE>

<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Returns the enum constant of this type with the specified name.</TD>
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<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>static&nbsp;<A HREF="../../../../../com/google/appengine/api/datastore/ImplicitTransactionManagementPolicy.html" title="enum in com.google.appengine.api.datastore">ImplicitTransactionManagementPolicy</A>[]</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../../../com/google/appengine/api/datastore/ImplicitTransactionManagementPolicy.html#values()">values</A></B>()</CODE>

<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Returns an array containing the constants of this enum type, in
the order they are declared.</TD>
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<TD><CODE>compareTo, equals, getDeclaringClass, hashCode, name, ordinal, toString, valueOf</CODE></TD>
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<TD><CODE>getClass, notify, notifyAll, wait, wait, wait</CODE></TD>
</TR>
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&nbsp;
<P>

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<A NAME="NONE"><!-- --></A><H3>
NONE</H3>
<PRE>
public static final <A HREF="../../../../../com/google/appengine/api/datastore/ImplicitTransactionManagementPolicy.html" title="enum in com.google.appengine.api.datastore">ImplicitTransactionManagementPolicy</A> <B>NONE</B></PRE>
<DL>
<DD>If a current transaction exists, use it, otherwise execute without a
 transaction.
<P>
<DL>
</DL>
</DL>
<HR>

<A NAME="AUTO"><!-- --></A><H3>
AUTO</H3>
<PRE>
public static final <A HREF="../../../../../com/google/appengine/api/datastore/ImplicitTransactionManagementPolicy.html" title="enum in com.google.appengine.api.datastore">ImplicitTransactionManagementPolicy</A> <B>AUTO</B></PRE>
<DL>
<DD>If a current transaction exists, use it, otherwise create one.
 The transaction will be committed before the method returns if the
 datastore operation completes successfully and rolled back if the
 datastore operation does not complete successfully.  No matter the type
 or quantity of entities provided, only one transaction will be created.
 This means that if you pass entities that belong to multiple entity groups
 into one of these methods and you have this policy enabled, you will
 receive an exception because transactions do not function across entity
 groups.
<P>
<DL>
</DL>
</DL>

<!-- ============ METHOD DETAIL ========== -->

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<A NAME="values()"><!-- --></A><H3>
values</H3>
<PRE>
public static <A HREF="../../../../../com/google/appengine/api/datastore/ImplicitTransactionManagementPolicy.html" title="enum in com.google.appengine.api.datastore">ImplicitTransactionManagementPolicy</A>[] <B>values</B>()</PRE>
<DL>
<DD>Returns an array containing the constants of this enum type, in
the order they are declared.  This method may be used to iterate
over the constants as follows:
<pre>
for (ImplicitTransactionManagementPolicy c : ImplicitTransactionManagementPolicy.values())
&nbsp;   System.out.println(c);
</pre>
<P>
<DD><DL>

<DT><B>Returns:</B><DD>an array containing the constants of this enum type, in
the order they are declared</DL>
</DD>
</DL>
<HR>

<A NAME="valueOf(java.lang.String)"><!-- --></A><H3>
valueOf</H3>
<PRE>
public static <A HREF="../../../../../com/google/appengine/api/datastore/ImplicitTransactionManagementPolicy.html" title="enum in com.google.appengine.api.datastore">ImplicitTransactionManagementPolicy</A> <B>valueOf</B>(java.lang.String&nbsp;name)</PRE>
<DL>
<DD>Returns the enum constant of this type with the specified name.
The string must match <I>exactly</I> an identifier used to declare an
enum constant in this type.  (Extraneous whitespace characters are 
not permitted.)
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>name</CODE> - the name of the enum constant to be returned.
<DT><B>Returns:</B><DD>the enum constant with the specified name
<DT><B>Throws:</B>
<DD><CODE>java.lang.IllegalArgumentException</CODE> - if this enum type has no constant
with the specified name
<DD><CODE>java.lang.NullPointerException</CODE> - if the argument is null</DL>
</DD>
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