78 lines
3.9 KiB
HTML
78 lines
3.9 KiB
HTML
<!--$Id: env_set_region_init.so,v 10.10 2000/05/31 15:10:00 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: db_env_set_region_init</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>db_env_set_region_init</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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db_env_set_region_init(int region_init);
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</pre></h3>
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<h1>Description</h1>
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<p>Page-fault shared regions into memory when initially creating or joining
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a Berkeley DB environment. In some applications, the expense of page-faulting
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the shared memory regions can affect performance, e.g., when the
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page-fault occurs while holding a lock, other lock requests can convoy
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and overall throughput may decrease. Setting <b>region_init</b> to a
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non-zero value specifies that shared regions be read or written, as
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appropriate, when the region is joined by the application. This forces
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the underlying virtual memory and file systems to instantiate both the
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necessary memory and the necessary disk space. This can also avoid
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out-of-disk space failures later on.
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<p>The db_env_set_region_init interface affects the entire application, not a single
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database or database environment.
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<p>While the db_env_set_region_init interface may be used to configure Berkeley DB at any time
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during the life of the application, it should normally be called before
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making any calls to the <a href="../api_c/env_create.html">db_env_create</a> or <a href="../api_c/db_create.html">db_create</a> functions.
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<p>The db_env_set_region_init function returns a non-zero error value on failure and 0 on success.
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<p>The database environment's initial behavior with respect to shared memory regions may also be set using the environment's
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<b>DB_CONFIG</b> file. The syntax of the entry in that file is a
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single line with the string "set_region_init", one or more whitespace characters,
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and the string "1". Because the <b>DB_CONFIG</b> file is read when the database
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environment is opened, it will silently overrule configuration done
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before that time.
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<h1>Errors</h1>
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<p><dl compact>
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<p><dt>EINVAL<dd>An invalid flag value or parameter was specified.
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</dl>
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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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</td></tr></table>
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<p><font size=1><a href="http://www.sleepycat.com">Copyright Sleepycat Software</a></font>
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