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7.5 KiB
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<!--$Id: env_remove.so,v 10.24 2000/12/06 14:40:11 bostic Exp $-->
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<!--Copyright 1997, 1998, 1999, 2000 by Sleepycat Software, Inc.-->
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<!--All rights reserved.-->
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<html>
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<head>
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<title>Berkeley DB: DBENV->remove</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,b+tree,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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<a name="2"><!--meow--></a>
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<table><tr valign=top>
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<td>
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<h1>DBENV->remove</h1>
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</td>
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<td width="1%">
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<a href="../api_c/c_index.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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<hr size=1 noshade>
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<tt>
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<h3><pre>
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#include <db.h>
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<p>
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int
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DBENV->remove(DB_ENV *, char *db_home, u_int32_t flags);
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</pre></h3>
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<h1>Description</h1>
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<p>The DBENV->remove function destroys a Berkeley DB environment, if it is not
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currently in use. The environment regions, including any backing files,
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are removed. Any log or database files and the environment directory are
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not removed.
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<p>The <b>db_home</b> argument to DBENV->remove is described in
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<a href="../ref/env/naming.html">Berkeley DB File Naming</a>.
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<p>If there are processes that have called <a href="../api_c/env_open.html">DBENV->open</a> without
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calling <a href="../api_c/env_close.html">DBENV->close</a> (i.e., there are processes currently using
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the environment), DBENV->remove will fail without further action,
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unless the <a href="../api_c/env_remove.html#DB_FORCE">DB_FORCE</a> flag is set, in which case
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DBENV->remove will attempt to remove the environment regardless
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of any processes still using it.
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<p>The result of attempting to forcibly destroy the environment when it is
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in use is unspecified. Processes using an environment often maintain open
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file descriptors for shared regions within it. On UNIX systems, the
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environment removal will usually succeed and processes that have already
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joined the region will continue to run in that region without change,
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however processes attempting to join the environment will either fail or
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create new regions. On other systems (e.g., Windows/NT), where the
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<b>unlink</b>(2) system call will fail if any process has an open
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file descriptor for the file, the region removal will fail.
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<p>Calling DBENV->remove should not be necessary for most applications,
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as the Berkeley DB environment is cleaned up as part of normal database recovery
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procedures, however, applications may wish to call DBENV->remove
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as part of application shutdown to free up system resources.
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Specifically, when the <a href="../api_c/env_open.html#DB_SYSTEM_MEM">DB_SYSTEM_MEM</a> flag was specified to
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<a href="../api_c/env_open.html">DBENV->open</a>, it may be useful to call DBENV->remove in order
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to release system shared memory segments that have been allocated.
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<p>In the case of catastrophic or system failure, database recovery must be
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performed (see <a href="../utility/db_recover.html">db_recover</a>), or the <a href="../api_c/env_open.html#DB_RECOVER">DB_RECOVER</a> and
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<a href="../api_c/env_open.html#DB_RECOVER_FATAL">DB_RECOVER_FATAL</a> flags to <a href="../api_c/env_open.html">DBENV->open</a> must be specified
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when the environment is re-opened. Alternatively, if recovery is not
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required because no database state is maintained across failures, and
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the <a href="../api_c/env_open.html#DB_SYSTEM_MEM">DB_SYSTEM_MEM</a> flag was not specified when the environment
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was created, it is possible to clean up an environment by removing all
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of the files in the environment directory that begin with the string
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prefix "__db", as no backing files are created in any other directory.
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<p>The <b>flags</b> value must be set to 0 or by bitwise inclusively <b>OR</b>'ing together one or more
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of the following values.
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<p><dl compact>
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<p><dt><a name="DB_FORCE">DB_FORCE</a><dd>If the <a href="../api_c/env_remove.html#DB_FORCE">DB_FORCE</a> flag is set, the environment is removed regardless
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of any processes that may still using it, and, no locks are acquired
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during this process. (Generally, the <a href="../api_c/env_remove.html#DB_FORCE">DB_FORCE</a> flag is only
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specified when applications were unable to shut down cleanly, and there
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is a risk that an application may have died holding a Berkeley DB lock.)
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<!--$Id: m4.env_flags,v 10.9 2000/06/29 22:54:10 bostic Exp $-->
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<p><dt><a name="DB_USE_ENVIRON">DB_USE_ENVIRON</a><dd>The Berkeley DB process' environment may be permitted to specify information to
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be used when naming files; see <a href="../ref/env/naming.html">Berkeley DB
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File Naming</a>. As permitting users to specify which files are used can
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create security problems, environment information will be used in file
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naming for all users only if the DB_USE_ENVIRON flag is set.
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<p><dt><a name="DB_USE_ENVIRON_ROOT">DB_USE_ENVIRON_ROOT</a><dd>The Berkeley DB process' environment may be permitted to specify information to
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be used when naming files; see <a href="../ref/env/naming.html">Berkeley DB
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File Naming</a>. As permitting users to specify which files are used can
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create security problems, if the DB_USE_ENVIRON_ROOT flag is set,
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environment information will be used for file naming only for users with
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appropriate permissions (e.g., on UNIX systems, users with a user-ID of 0).
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</dl>
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<p>In multi-threaded applications, only a single thread may call
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DBENV->remove.
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<p>A DB_ENV handle which has already been used to open an
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environment should not be used to call the DBENV->remove function, a new
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DB_ENV handle should be created for that purpose.
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<p>Once DBENV->remove has been called, regardless of its return,
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the Berkeley DB environment handle may not be accessed again.
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<p>The DBENV->remove function returns a non-zero error value on failure and 0 on success.
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<h1>Errors</h1>
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<p><dl compact>
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<p><dt>EBUSY<dd>The shared memory region was in use and the force flag was not set.
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</dl>
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<p>The DBENV->remove function may fail and return a non-zero error for errors specified for other Berkeley DB and C library or system functions.
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If a catastrophic error has occurred, the DBENV->remove function may fail and return
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<a href="../ref/program/errorret.html#DB_RUNRECOVERY">DB_RUNRECOVERY</a>, in which case all subsequent Berkeley DB calls will fail
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in the same way.
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<h1>See Also</h1>
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<a href="../api_c/env_close.html">DBENV->close</a>,
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<a href="../api_c/env_create.html">db_env_create</a>,
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<a href="../api_c/env_open.html">DBENV->open</a>,
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<a href="../api_c/env_remove.html">DBENV->remove</a>,
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<a href="../api_c/db_err.html">DBENV->err</a>,
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<a href="../api_c/env_strerror.html">db_strerror</a>,
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<a href="../api_c/env_version.html">db_version</a>,
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<a href="../api_c/env_set_cachesize.html">DBENV->set_cachesize</a>,
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<a href="../api_c/env_set_errcall.html">DBENV->set_errcall</a>,
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<a href="../api_c/env_set_errfile.html">DBENV->set_errfile</a>,
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<a href="../api_c/env_set_errpfx.html">DBENV->set_errpfx</a>,
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<a href="../api_c/env_set_flags.html">DBENV->set_flags</a>,
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<a href="../api_c/env_set_mutexlocks.html">DBENV->set_mutexlocks</a>,
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<a href="../api_c/env_set_paniccall.html">DBENV->set_paniccall</a>,
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and
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<a href="../api_c/env_set_verbose.html">DBENV->set_verbose</a>.
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</tt>
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<table><tr><td><br></td><td width="1%">
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<a href="../api_c/c_index.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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