bdb/tcl/docs/txn.html


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<H2>
<A NAME="Transaction Commands"></A>Transaction Commands</H2>
Transactions are used in a manner similar to the other subsystems.&nbsp;
We create a handle to the transaction and&nbsp; then use it for a variety
of operations.&nbsp; Some of the transaction commands use the environment
instead.&nbsp; Those are presented first.&nbsp; The transaction command
handle returned is the handle used by the various commands that can be
transaction protected, such as <A HREF="../../docs/api_tcl/db_cursor.html">cursors</A>.<BR>

<HR WIDTH="100%">
<P><B>> &lt;env> txn_checkpoint [-kbyte <I>kb</I>] [-min <I>min</I>]</B>
<P>This command causes a checkpoint of the transaction region.&nbsp; It
is a direct translation of the <A HREF="../../docs/api_c/txn_checkpoint.html">txn_checkpoint
</A>function.&nbsp;
It returns either a 0 (for success), a DB error message or it throws a
Tcl error with a system message.&nbsp; The arguments are:
<UL>
<LI>
<B>-kbyte </B>causes the checkpoint to occur only if <B><I>kb</I></B> kilobytes
of log data has been written since the last checkpoint</LI>

<LI>
<B>-min</B> causes the checkpoint to occur only if <B><I>min</I></B> minutes
have passed since the last checkpoint</LI>
</UL>

<HR WIDTH="100%">
<BR><B>> &lt;env> txn_stat</B>
<P>This command returns transaction statistics.&nbsp; It is a direct translation
of the <A HREF="../../docs/api_c/txn_stat.html">txn_stat</A> function.&nbsp;
It will return a list of name/value pairs that correspond to the DB_TXN_STAT
structure.
<HR WIDTH="100%">
<BR><B>>&nbsp; &lt;txn> id</B>
<P>This command returns the transaction id.&nbsp; It is a direct call to
the <A HREF="../../docs/api_c/txn_id.html">txn_id</A> function.&nbsp; The
typical use of this identifier is as the <B><I>locker</I></B> value for
the <A HREF="lock.html">lock_get</A> and <A HREF="lock.html">lock_vec</A>
calls.
<HR WIDTH="100%">
<BR><B>> &lt;txn> prepare</B>
<P>This command initiates a two-phase commit.&nbsp; It is a direct call
to the <A HREF="../../docs/api_c/txn_prepare.html">txn_prepare</A> function.&nbsp;
It returns either a 0 (for success), a DB error message or it throws a
Tcl error with a system message.
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