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494 lines
18 KiB
HTML
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>DB_ENV->txn_stat()</title>
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<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
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<link rel="start" href="index.html" title="Berkeley DB C API Reference" />
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<link rel="up" href="txn.html" title="Chapter 12. The DB_TXN Handle" />
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<link rel="prev" href="txncheckpoint.html" title="DB_ENV->txn_checkpoint()" />
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<div xmlns="" class="navheader">
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<p>Library Version 11.2.5.3</p>
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</div>
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<table width="100%" summary="Navigation header">
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<tr>
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<th colspan="3" align="center">DB_ENV->txn_stat()</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="txncheckpoint.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 12.
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The DB_TXN Handle
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</th>
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<td width="20%" align="right"> <a accesskey="n" href="txnstat_print.html">Next</a></td>
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</tr>
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</table>
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<hr />
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</div>
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<div class="sect1" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h2 class="title" style="clear: both"><a id="txnstat"></a>DB_ENV->txn_stat()</h2>
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</div>
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</div>
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</div>
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<pre class="programlisting">#include <db.h>
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int
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DB_ENV->txn_stat(DB_ENV *env, DB_TXN_STAT **statp, u_int32_t flags); </pre>
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<p>
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The <code class="methodname">DB_ENV->txn_stat()</code> method returns the transaction subsystem
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statistics.
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</p>
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<p>
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The <code class="methodname">DB_ENV->txn_stat()</code> method creates a statistical structure of type
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<code class="literal">DB_TXN_STAT</code> and copies a pointer to it into a user-specified memory
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location.
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</p>
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<p>
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Statistical structures are stored in allocated memory. If
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application-specific allocation routines have been declared (see
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<a class="xref" href="envset_alloc.html" title="DB_ENV->set_alloc()">DB_ENV->set_alloc()</a>
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for more information), they are used to allocate the memory;
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otherwise, the standard C library <span class="bold"><strong>malloc</strong></span>(3) is used. The caller is responsible
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for deallocating the memory. To deallocate the memory, free the
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memory reference; references inside the returned memory need not be
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individually freed.
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</p>
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<p>
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The following DB_TXN_STAT fields will be filled in:
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</p>
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<div class="itemizedlist">
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<ul type="disc">
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<li>
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<p>
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<span class="bold"><strong>u_int32_t st_inittxns;</strong></span>
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</p>
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<p>
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The initial number of transactions configured.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>DB_LSN st_last_ckp;</strong></span>
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</p>
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<p>
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The LSN of the last checkpoint.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>u_int32_t st_last_txnid;</strong></span>
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</p>
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<p>
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The last transaction ID allocated.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>u_int32_t st_maxnactive;</strong></span>
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</p>
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<p>
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The maximum number of active transactions at any one time.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>u_int32_t st_maxnsnapshot;</strong></span>
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</p>
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<p>
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The maximum number of transactions on the snapshot list at any one
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time.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>u_int32_t st_maxtxns;</strong></span>
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</p>
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<p>
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The maximum number of active transactions configured.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>uintmax_t st_naborts;</strong></span>
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</p>
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<p>
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The number of transactions that have aborted.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>u_int32_t st_nactive;</strong></span>
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</p>
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<p>
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The number of transactions that are currently active.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>uintmax_t st_nbegins;</strong></span>
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</p>
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<p>
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The number of transactions that have begun.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>uintmax_t st_ncommits;</strong></span>
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</p>
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<p>
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The number of transactions that have committed.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>u_int32_t st_nrestores;</strong></span>
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</p>
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<p>
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The number of transactions that have been restored.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>u_int32_t st_nsnapshot;</strong></span>
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</p>
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<p>
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The number of transactions on the snapshot list. These are
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transactions which modified a database opened with
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<a class="link" href="dbopen.html#dbopen_DB_MULTIVERSION">DB_MULTIVERSION</a>,
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and which have committed or aborted, but the copies of pages they
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created are still in the cache.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>uintmax_t st_region_nowait;</strong></span>
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</p>
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<p>
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The number of times that a thread of control was able to obtain the
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transaction region mutex without waiting.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>uintmax_t st_region_wait;</strong></span>
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</p>
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<p>
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The number of times that a thread of control was forced to wait before
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obtaining the transaction region mutex.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>roff_t st_regsize;</strong></span>
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</p>
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<p>
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The region size, in bytes.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>time_t st_time_ckp;</strong></span>
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</p>
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<p>
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The time the last completed checkpoint finished (as the number of
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seconds since the Epoch, returned by the IEEE/ANSI Std 1003.1 (POSIX)
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<span class="bold"><strong>time</strong></span> function).
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>DB_TXN_ACTIVE *st_txnarray;</strong></span>
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</p>
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<p>
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A pointer to an array of <span class="bold"><strong>st_nactive</strong></span>
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DB_TXN_ACTIVE structures, describing the currently active
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transactions. The following fields of the DB_TXN_ACTIVE structure will
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be filled in:
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</p>
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<div class="itemizedlist">
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<ul type="circle">
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<li>
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<p>
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<span class="bold"><strong>u_int32_t txnid;</strong></span>
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</p>
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<p>
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The transaction ID of the transaction.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>u_int32_t parentid;</strong></span>
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</p>
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<p>
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The transaction ID of the parent transaction (or 0, if no parent).
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>pid_t pid;</strong></span>
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</p>
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<p>
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The process ID of the originator of the transaction.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>db_threadid_t tid;</strong></span>
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</p>
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<p>
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The thread of control ID of the originator of the transaction.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>DB_LSN lsn;</strong></span>
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</p>
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<p>
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The current log sequence number when the transaction was begun.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>DB_LSN read_lsn;</strong></span>
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</p>
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<p>
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The log sequence number of reads for snapshot transactions.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>u_int32_t mvcc_ref;</strong></span>
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</p>
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<p>
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The number of buffer copies created by this transaction that remain
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in cache.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>u_int32_t priority;</strong></span>
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</p>
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<p>
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This transaction's deadlock resolution priority.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>u_int32_t status;</strong></span>
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</p>
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<p>
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Provides one of the following constants,
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indicating the transaction status:
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</p>
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<table class="simplelist" border="0" summary="Simple list">
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<tr>
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<td>TXN_ABORTED</td>
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</tr>
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<tr>
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<td>TXN_COMMITTED</td>
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</tr>
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<tr>
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<td>TXN_NEED_ABORT</td>
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</tr>
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<tr>
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<td>TXN_PREPARED</td>
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</tr>
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<tr>
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<td>TXN_RUNNING</td>
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</tr>
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</table>
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</li>
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<li>
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<p>
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<span class="bold"><strong>u_int32_t xa_status;</strong></span>
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</p>
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<p>
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Provides one of the following constants, which indicate the
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XA status:
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</p>
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<table class="simplelist" border="0" summary="Simple list">
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<tr>
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<td>TXN_XA_ACTIVE</td>
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</tr>
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<tr>
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<td>TXN_XA_DEADLOCKED</td>
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</tr>
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<tr>
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<td>TXN_XA_IDLE</td>
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</tr>
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<tr>
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<td>TXN_XA_PREPARED</td>
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</tr>
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<tr>
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<td>TXN_XA_ROLLEDBACK</td>
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</tr>
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</table>
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</li>
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<li>
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<p>
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<span class="bold"><strong>u_int8_t gid[DB_GID_SIZE];</strong></span>
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</p>
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<p>
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If the transaction was prepared using
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<a class="xref" href="txnprepare.html" title="DB_TXN->prepare()">DB_TXN->prepare()</a>, then
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<span class="bold"><strong>gid</strong></span> contains the
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transaction's Global ID. Otherwise,
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<span class="bold"><strong>gid's</strong></span> contents are undefined.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>char name[];</strong></span>
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</p>
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<p>
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If a name was specified for the transaction, up to the first 50 bytes
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of that name, followed by a nul termination byte.
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</p>
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</li>
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</ul>
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</div>
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</li>
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</ul>
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</div>
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<p>
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The <code class="methodname">DB_ENV->txn_stat()</code> method may not be called before the
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<a class="xref" href="envopen.html" title="DB_ENV->open()">DB_ENV->open()</a> method is called.
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</p>
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<p>
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The <code class="methodname">DB_ENV->txn_stat()</code> <span>
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<span>
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method returns a non-zero error value on failure and 0 on success.
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</span>
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</span>
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</p>
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<div class="sect2" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h3 class="title"><a id="idp62839144"></a>Parameters</h3>
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</div>
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</div>
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</div>
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<div class="sect3" lang="en" xml:lang="en">
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<div class="titlepage">
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||
<div>
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<div>
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<h4 class="title"><a id="idp62839856"></a>statp</h4>
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</div>
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</div>
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</div>
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<p>
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The <span class="bold"><strong>statp</strong></span> parameter references memory
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into which a pointer to the allocated statistics structure is copied.
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</p>
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</div>
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<div class="sect3" lang="en" xml:lang="en">
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<div class="titlepage">
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||
<div>
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<div>
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<h4 class="title"><a id="idp62871592"></a>flags</h4>
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</div>
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</div>
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</div>
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<p>
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The <span class="bold"><strong>flags</strong></span> parameter must be set to 0
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or the following value:
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</p>
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<div class="itemizedlist">
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<ul type="disc">
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||
<li>
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<p>
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<code class="literal">DB_STAT_CLEAR</code>
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</p>
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<p>
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Reset statistics after returning their values.
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</p>
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</li>
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||
</ul>
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||
</div>
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||
</div>
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||
</div>
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||
<div class="sect2" lang="en" xml:lang="en">
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||
<div class="titlepage">
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||
<div>
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||
<div>
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||
<h3 class="title"><a id="idp62867864"></a>Errors</h3>
|
||
</div>
|
||
</div>
|
||
</div>
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||
<p>
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||
The <code class="methodname">DB_ENV->txn_stat()</code> <span>
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<span>
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||
method may fail and return one of the following non-zero errors:
|
||
</span>
|
||
|
||
</span>
|
||
</p>
|
||
<div class="sect3" lang="en" xml:lang="en">
|
||
<div class="titlepage">
|
||
<div>
|
||
<div>
|
||
<h4 class="title"><a id="idp62875480"></a>EINVAL</h4>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
<p>
|
||
An invalid flag value or parameter was specified.
|
||
</p>
|
||
</div>
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||
</div>
|
||
<div class="sect2" lang="en" xml:lang="en">
|
||
<div class="titlepage">
|
||
<div>
|
||
<div>
|
||
<h3 class="title"><a id="idp62770624"></a>Class</h3>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
<p>
|
||
<a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a>, <a class="link" href="txn.html" title="Chapter 12. The DB_TXN Handle">DB_TXN</a>
|
||
</p>
|
||
</div>
|
||
<div class="sect2" lang="en" xml:lang="en">
|
||
<div class="titlepage">
|
||
<div>
|
||
<div>
|
||
<h3 class="title"><a id="idp62878760"></a>See Also</h3>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
<p>
|
||
<a class="xref" href="txn.html#txnlist" title="Transaction Subsystem and Related Methods">Transaction Subsystem and Related Methods</a>
|
||
</p>
|
||
</div>
|
||
</div>
|
||
<div class="navfooter">
|
||
<hr />
|
||
<table width="100%" summary="Navigation footer">
|
||
<tr>
|
||
<td width="40%" align="left"><a accesskey="p" href="txncheckpoint.html">Prev</a> </td>
|
||
<td width="20%" align="center">
|
||
<a accesskey="u" href="txn.html">Up</a>
|
||
</td>
|
||
<td width="40%" align="right"> <a accesskey="n" href="txnstat_print.html">Next</a></td>
|
||
</tr>
|
||
<tr>
|
||
<td width="40%" align="left" valign="top">DB_ENV->txn_checkpoint() </td>
|
||
<td width="20%" align="center">
|
||
<a accesskey="h" href="index.html">Home</a>
|
||
</td>
|
||
<td width="40%" align="right" valign="top"> DB_ENV->txn_stat_print()</td>
|
||
</tr>
|
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</table>
|
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</div>
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</body>
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</html>
|