txn.html 2.88 KB
Newer Older
unknown's avatar
unknown committed
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62
<!--$Id: txn.so,v 11.12 2000/02/19 20:57:57 bostic Exp $-->
<!--$Id: m4.tcl,v 11.17 2000/04/24 17:31:11 sue Exp $-->
<!--Copyright 1997, 1998, 1999, 2000 by Sleepycat Software, Inc.-->
<!--All rights reserved.-->
<html>
<head>
<title>Berkeley DB: env txn</title>
<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit.">
<meta name="keywords" content="embedded,database,programmatic,toolkit,b+tree,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,java,C,C++">
</head>
<body bgcolor=white>
        <a name="2"><!--meow--></a>    
<table><tr valign=top>
<td>
<h1><i>env</i> <b>txn</b></h1>
</td>
<td width="1%">
<a href="../api_tcl/tcl_index.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a>
</td></tr></table>
<hr size=1 noshade>
<tt>
<h3><pre>env txn
	[-nosync]
	[-nowait]
	[-parent txnid]
	[-sync]
</pre></h3>
<h1>Description</h1>
<p>The <i>env</i> <b>txn</b> command begins a transaction.  The returned transaction
handle is bound to a Tcl command of the form <b>env.txnX</b>, where X
is an integer starting at 0 (e.g., env0.txn0 and env0.txn1).  It is
through this Tcl command that the script accesses the transaction methods.
<p>The options are as follows:
<p><dl compact>
<p><dt>-nosync<dd>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), i.e.,
database integrity will be maintained but it is possible that this
transaction may be undone during recovery instead of being redone.
<p>This behavior may be set for an entire Berkeley DB environment as part of
the <b>berkdb env</b> interface.
<p><dt>-nowait<dd>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><dt>-parent txnid<dd>Create the new transaction as a nested transaction, with the specified
transaction indicated as its parent.  Transactions may be nested to any
level.
<p><dt>-sync<dd>Synchronously flush the log when this transaction commits or prepares. This
means the transaction will exhibit all of the ACID (atomicity, consistency
and isolation and durability) properties.
<p>This behavior is the default for Berkeley DB environments unless the
<b>-nosync</b> option was specified to the <b>berkdb env</b> interface.
</dl>
<p>The <i>env</i> <b>txn</b> command returns a transaction handle on success.
<p>In the case of error, a Tcl error is thrown.
</tt>
<table><tr><td><br></td><td width="1%">
<a href="../api_tcl/tcl_index.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a>
</td></tr></table>
<p><font size=1><a href="http://www.sleepycat.com">Copyright Sleepycat Software</a></font>
</body>
</html>