<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>env txn</title> <link rel="stylesheet" href="apiReference.css" type="text/css" /> <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> <link rel="start" href="index.html" title="Berkeley DB TCL API Reference" /> <link rel="up" href="tclapi.html" title="Chapter 1. Berkeley DB Tcl APIs" /> <link rel="prev" href="env_remove.html" title="berkdb envremove" /> <link rel="next" href="txn_abort.html" title="txn abort" /> </head> <body> <div xmlns="" class="navheader"> <div class="libver"> <p>Library Version 11.2.5.3</p> </div> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center"><span xmlns="http://www.w3.org/1999/xhtml" class="emphasis"><em>env</em></span> txn</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="env_remove.html">Prev</a> </td> <th width="60%" align="center">Chapter 1. Berkeley DB Tcl APIs </th> <td width="20%" align="right"> <a accesskey="n" href="txn_abort.html">Next</a></td> </tr> </table> <hr /> </div> <div class="sect1" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h2 class="title" style="clear: both"><a id="txn"></a><span class="emphasis"><em>env</em></span> txn</h2> </div> </div> </div> <pre class="programlisting">env txn [-nosync] [-nowait] [-parent txnid] [-sync] </pre> <p> The <span class="emphasis"><em>env</em></span> <span class="bold"><strong>txn</strong></span> command begins a transaction. The returned transaction handle is bound to a Tcl command of the form <span class="bold"><strong>env.txnX</strong></span>, where X is an integer starting at 0 (for example, env0.txn0 and env0.txn1). It is through this Tcl command that the script accesses the transaction methods. </p> <p> The options are as follows: </p> <div class="itemizedlist"> <ul type="disc"> <li> <p> <span class="bold"><strong>-nosync</strong></span> </p> <p> Do not synchronously flush the log when this transaction commits or prepares. This means the transaction will exhibit the ACI (atomicity, consistency, and isolation) properties, but not D (durability); that is, database integrity will be maintained, but it is possible that this transaction may be undone during recovery instead of being redone. </p> <p> This behavior may be set for an entire Berkeley DB environment as part of the <span class="bold"><strong>berkdb env</strong></span> call. </p> </li> <li> <p> <span class="bold"><strong>-nowait</strong></span> </p> <p> If a lock is unavailable for any Berkeley DB operation performed in the context of this transaction, throw a Tcl error immediately instead of blocking on the lock. </p> </li> <li> <p> <span class="bold"><strong>-parent txnid</strong></span> </p> <p> Create the new transaction as a nested transaction, with the specified transaction indicated as its parent. Transactions may be nested to any level. </p> </li> <li> <p> <span class="bold"><strong>-sync</strong></span> </p> <p> Synchronously flush the log when this transaction commits or prepares. This means the transaction will exhibit all of the ACID (atomicity, consistency, isolation, and durability) properties. </p> <p> This behavior is the default for Berkeley DB environments unless the <span class="bold"><strong>-nosync</strong></span> option was specified to the <span class="bold"><strong>berkdb env</strong></span> call. </p> </li> </ul> </div> <p> The <span class="emphasis"><em>env</em></span> <span class="bold"><strong>txn</strong></span> command returns a transaction handle on success. </p> <p> In the case of error, a Tcl error is thrown. </p> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="env_remove.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="tclapi.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="txn_abort.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">berkdb envremove </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> <span class="emphasis"><em>txn</em></span> abort</td> </tr> </table> </div> </body> </html>