84 lines
3.9 KiB
HTML
84 lines
3.9 KiB
HTML
<!--$Id: db_set_append_recno.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: DB->set_append_recno</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>DB->set_append_recno</b>
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</td>
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<td align=right>
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<a href="../api_c/api_core.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>
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#include <db.h>
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<p>
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int
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DB->set_append_recno(DB *,
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int (*db_append_recno_fcn)(DB *dbp, DBT *data, db_recno_t recno));
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</pre></b>
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<hr size=1 noshade>
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<b>Description: DB->set_append_recno</b>
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<p>When using the <a href="../api_c/db_put.html#DB_APPEND">DB_APPEND</a> option of the <a href="../api_c/db_put.html">DB->put</a> method,
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it may be useful to modify the stored data based on the generated key.
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If a callback function is specified using the
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DB->set_append_recno method, it will be called after the record number
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has been selected, but before the data has been stored.</p>
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<p>The DB->set_append_recno method configures operations performed using the specified
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<a href="../api_c/db_class.html">DB</a> handle, not all operations performed on the underlying
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database.</p>
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<p>The DB->set_append_recno method may not be called after the <a href="../api_c/db_open.html">DB->open</a> method is called.
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</p>
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<p>The DB->set_append_recno method
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returns a non-zero error value on failure
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and 0 on success.
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</p>
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<b>Parameters</b> <br>
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<b>db_append_recno_fcn</b><ul compact><li>The <b>db_append_recno_fcn</b> parameter is a function to call after
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the record number has been selected but before the data has been stored
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into the database. The function takes three parameters:
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<br>
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<b><b>db</b></b><ul compact><li>The <b>db</b> parameter is the enclosing database handle.</ul>
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<b><b>dbt</b></b><ul compact><li>The <b>dbt</b> parameter is the data <a href="../api_c/dbt_class.html">DBT</a> to be stored.</ul>
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<b><b>recno</b></b><ul compact><li>The <b>recno</b> parameter is the generated record number.</ul>
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<br>
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<p>The called function may modify the data <a href="../api_c/dbt_class.html">DBT</a>. If the function
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needs to allocate memory for the <b>data</b> field, the <b>flags</b>
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field of the returned <a href="../api_c/dbt_class.html">DBT</a> should be set to
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DB_DBT_APPMALLOC, which indicates that Berkeley DB should free the
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memory when it is done with it.</p>
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<p>The callback function must return 0 on success and <b>errno</b> or
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a value outside of the Berkeley DB error name space on failure.</p>
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<p>Berkeley DB is not re-entrant. Callback functions should not attempt to make
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library calls (for example, to release locks or close open handles).
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Re-entering Berkeley DB is not guaranteed to work correctly, and the results
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are undefined.</p></ul>
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<br>
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<br><b>Errors</b>
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<p>The DB->set_append_recno method
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may fail and return one of the following non-zero errors:</p>
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<br>
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<b>EINVAL</b><ul compact><li>If the method was called after <a href="../api_c/db_open.html">DB->open</a> was called; or if an
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invalid flag value or parameter was specified.</ul>
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<br>
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<hr size=1 noshade>
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<br><b>Class</b>
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<a href="../api_c/db_class.html">DB</a>
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<br><b>See Also</b>
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<a href="../api_c/db_list.html">Databases and Related Methods</a>
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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_c/api_core.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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