110 lines
4.9 KiB
HTML
110 lines
4.9 KiB
HTML
<!--$Id: seq_open.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: DbSequence::open</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>DbSequence::open</b>
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</td>
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<td align=right>
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<a href="../api_cxx/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_cxx.h>
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<p>
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int
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int
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DbSequence::open(DbTxn *txnid, Dbt *key, u_int32_t flags);
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<p>
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int
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DbSequence::get_dbp(Db **dbp);
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<p>
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int
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DbSequence::get_key(Dbt *key);
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</pre></b>
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<hr size=1 noshade>
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<b>Description: DbSequence::open</b>
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<p>The DbSequence::open method opens the sequence represented by the <b>key</b>.
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The key must be compatible with the underlying database specified in the
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corresponding call to <a href="../api_c/seq_class.html">db_sequence_create</a>.</p>
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<b>Parameters</b> <br>
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<b>key</b><ul compact><li>The <b>key</b> specifies which record in the database stores
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the persistent sequence data.</ul>
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<b>flags</b><ul compact><li>The <b>flags</b> parameter must be set to 0 or by bitwise inclusively <b>OR</b>'ing together one
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or more of the following values:
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<br>
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<b><a name="DB_CREATE">DB_CREATE</a></b><ul compact><li>Create the sequence. If the sequence does not already exist and the
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DB_CREATE flag is not specified, the DbSequence::open will fail.</ul>
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<b><a name="DB_EXCL">DB_EXCL</a></b><ul compact><li>Return an error if the sequence already exists. The <a href="../api_cxx/db_open.html#DB_EXCL">DB_EXCL</a>
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flag is only meaningful when specified with the <a href="../api_cxx/env_open.html#DB_CREATE">DB_CREATE</a>
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flag.</ul>
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<b><a name="DB_THREAD">DB_THREAD</a></b><ul compact><li>Cause the <a href="../api_cxx/seq_class.html">DbSequence</a> handle returned by DbSequence::open to be
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<i>free-threaded</i>; that is, usable by multiple threads within a
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single address space. Note that if multiple threads create multiple
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sequences using the same database handle that handle must have been
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opened specifying <a name="DB_THREAD">DB_THREAD</a>.</ul>
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<br></ul>
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<b>txnid</b><ul compact><li>If the operation is part of an application-specified transaction, the
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<b>txnid</b> parameter is a transaction handle returned from
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<a href="../api_cxx/txn_begin.html">DbEnv::txn_begin</a>; if the operation is part of a Berkeley DB Concurrent Data Store group, the
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<b>txnid</b> parameter is a handle returned from
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<a href="../api_cxx/env_cdsgroup_begin.html">DbEnv::cdsgroup_begin</a>; otherwise NULL.
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If no transaction handle is
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specified, but the
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operation occurs in a transactional
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database,
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the operation will be implicitly transaction protected.
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Transactionally protected operations on a <a href="../api_cxx/seq_class.html">DbSequence</a> handle
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require the <a href="../api_cxx/seq_class.html">DbSequence</a> handle itself be transactionally
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protected during its open if the open creates the sequence.</ul>
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<br>
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<hr size=1 noshade>
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<b>Description: DbSequence::get_dbp</b>
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<p>The DbSequence::get_dbp method returns the database handle.</p>
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<b>Parameters</b> <br>
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<b>dbp</b><ul compact><li>The <b>dbp</b> parameter references memory into which
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a pointer to the database handle is copied.</ul>
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<br>
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<p>The DbSequence::get_dbp method may be called at any time during the life of the
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application.</p>
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<p>The DbSequence::get_dbp method
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either returns a non-zero error value
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or throws an exception that encapsulates a non-zero error value on
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failure, and returns 0 on success.
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</p>
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<hr size=1 noshade>
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<b>Description: DbSequence::get_key</b>
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<p>The DbSequence::get_key method returns the key for the sequence.</p>
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<b>Parameters</b> <br>
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<b>key</b><ul compact><li>The <b>key</b> parameter references memory into which
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a pointer to the key data is copied.</ul>
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<br>
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<p>The DbSequence::get_key method may be called at any time during the life of the
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application.</p>
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<p>The DbSequence::get_key method
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either returns a non-zero error value
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or throws an exception that encapsulates a non-zero error value on
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failure, and returns 0 on success.
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</p>
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<hr size=1 noshade>
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<br><b>Class</b>
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<a href="../api_cxx/seq_class.html">DbSequence</a>
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<br><b>See Also</b>
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<a href="../api_cxx/seq_list.html">Sequences 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_cxx/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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