64 lines
3.0 KiB
HTML
64 lines
3.0 KiB
HTML
<!--$Id: txn.html 63573 2008-05-23 21:43:21Z trent.nelson $-->
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<!--$Id: txn.html 63573 2008-05-23 21:43:21Z trent.nelson $-->
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<!--Copyright (c) 1997,2008 Oracle. All rights reserved.-->
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<!--See the file LICENSE for redistribution information.-->
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<html>
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<head>
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<title>Berkeley DB: env txn</title>
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<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit.">
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<meta name="keywords" content="embedded,database,programmatic,toolkit,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++">
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</head>
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<body bgcolor=white>
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<table width="100%"><tr valign=top>
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<td>
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<b><i>env</i> <b>txn</b></b>
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</td>
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<td align=right>
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<a href="../api_tcl/api_tcl.html"><img src="../images/api.gif" alt="API"></a>
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<a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a></td>
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</tr></table>
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<hr size=1 noshade>
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<tt>
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<b><pre>env txn
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[-nosync]
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[-nowait]
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[-parent txnid]
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[-sync]
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</pre></b>
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<b>Description(env txn)</b>
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<p>The <i>env</i> <b>txn</b> command begins a transaction. The returned transaction
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handle is bound to a Tcl command of the form <b>env.txnX</b>, where
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X is an integer starting at 0 (for example, env0.txn0 and env0.txn1).
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It is through this Tcl command that the script accesses the transaction
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methods.</p>
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<p>The options are as follows:</p>
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<br>
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<b>-nosync</b><ul compact><li>Do not synchronously flush the log when this transaction commits or
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prepares. This means the transaction will exhibit the ACI (atomicity,
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consistency, and isolation) properties, but not D (durability); that
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is, database integrity will be maintained, but it is possible that this
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transaction may be undone during recovery instead of being redone.
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<p>This behavior may be set for an entire Berkeley DB environment as part of the
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<b>berkdb env</b> call.</p></ul>
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<b>-nowait</b><ul compact><li>If a lock is unavailable for any Berkeley DB operation performed in the context
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of this transaction, throw a Tcl error immediately instead of blocking on
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the lock.</ul>
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<b>-parent txnid</b><ul compact><li>Create the new transaction as a nested transaction, with the specified
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transaction indicated as its parent. Transactions may be nested to any
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level.</ul>
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<b>-sync</b><ul compact><li>Synchronously flush the log when this transaction commits or prepares.
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This means the transaction will exhibit all of the ACID (atomicity,
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consistency, isolation, and durability) properties.
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<p>This behavior is the default for Berkeley DB environments unless the
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<b>-nosync</b> option was specified to the <b>berkdb env</b> call.</p></ul>
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<br>
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<p>The <i>env</i> <b>txn</b> command returns a transaction handle on success.</p>
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<p>In the case of error, a Tcl error is thrown.</p>
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</tt>
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<table width="100%"><tr><td><br></td><td align=right>
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<a href="../api_tcl/api_tcl.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a>
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</td></tr></table>
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<p><font size=1>Copyright (c) 1996,2008 Oracle. All rights reserved.</font>
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</body>
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</html>
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