db/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>-force</b>causes the checkpoint to occur regardless of inactivity

<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>
<b>-min</b> causes the checkpoint to occur only if <b><i>min</i></b> minutes
have passed since the last checkpoint
</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>> &lt;env> txn_id_set&nbsp;</b><i> current max</i>
<p>This is a diagnosic command that sets the next transaction id to be
allocated and the maximum transaction
<br>id, which is the point at which the relcaimation algorthm is triggered.
<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.
<hr WIDTH="100%"><a NAME="> <env> lock_vec"></a><b>> &lt;env> txn_timeout
<i>timeout</i></b>
<p>This command sets thetransaction timeout for transactions started in
the future in this environment.&nbsp; The timeout is in micorseconds.
<br>&nbsp;
<br>&nbsp;
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