docs/gsg_txn/CXX/txnindices.html

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   6     <title>Secondary Indices with Transaction Applications</title>
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  17         <p>Library Version 11.2.5.3</p>
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  21           <th colspan="3" align="center">Secondary Indices with Transaction Applications</th>
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  24           <td width="20%" align="left"><a accesskey="p" href="txncursor.html">Prev</a> </td>
  25           <th width="60%" align="center">Chapter 3. Transaction Basics</th>
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  35             <h2 class="title" style="clear: both"><a id="txnindices"></a>Secondary Indices with Transaction Applications</h2>
  36           </div>
  37         </div>
  38       </div>
  39       <p>
  40             You can use transactions with your secondary indices so long as you
  41
  42             <span>
  43                 open the secondary index so that it supports transactions (that is,
  44                 you wrap the database open in a transaction, or use auto commit,
  45                 in the same way as when you open a primary transactional database).
  46             </span>
  47
  48
  49
  50             <span>
  51                 In addition, you must make sure that when you associate the
  52                 secondary index with the primary database, the association is
  53                 performed using a transaction. The easiest thing to do here is
  54                 to simply specify <code class="literal">DB_AUTO_COMMIT</code> when you
  55                 perform the association.
  56             </span>
  57         </p>
  58       <p>
  59             All other aspects of using secondary indices with transactions are
  60             identical to using secondary indices without transactions. In
  61             addition, transaction-protecting
  62                 <span>
  63                     cursors opened against secondary indices is performed in
  64                     exactly the same way as when you use transactional cursors
  65                     against a primary database.
  66                 </span>
  67
  68                     See <a class="xref" href="txncursor.html" title="Transactional Cursors">Transactional Cursors</a> for details.
  69         </p>
  70       <p>
  71             Note that when you use transactions to protect your database writes, your secondary indices are protected from
  72             corruption because updates to the primary and the secondaries are performed in a single atomic transaction.
  73         </p>
  74       <p>
  75             For example:
  76         </p>
  77       <pre class="programlisting">#include &lt;db_cxx.h&gt;
  78
  79 ...
  80
  81 // Environment and primary database open omitted
  82 ...
  83
  84 Db my_index(&amp;envp, 0);    // Secondary
  85
  86 // Open the secondary
  87 my_index.open(NULL,              // Transaction pointer
  88               "my_secondary.db", // On-disk file that holds the database.
  89               NULL,              // Optional logical database name
  90               DB_BTREE,          // Database access method
  91               DB_AUTO_COMMIT,    // Open flags.
  92               0);                // File mode (using defaults)
  93
  94 // Now associate the primary and the secondary
  95 my_database.associate(NULL,             // Txn id
  96                       &amp;my_index,        // Associated secondary database
  97                       get_sales_rep,    // Callback used for key
  98                                         // extraction. This is described
  99                                         // in the Getting Started guide.
 100                       DB_AUTO_COMMIT);  // Flags </pre>
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 108             <a accesskey="u" href="usingtxns.html">Up</a>
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