1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
|
<!--$Id: env_set_cachesize.so,v 10.19 2000/05/20 16:29:11 bostic Exp $-->
<!--$Id: m4.cachesize,v 10.7 2000/02/11 18:54:45 bostic Exp $-->
<!--Copyright 1997, 1998, 1999, 2000 by Sleepycat Software, Inc.-->
<!--All rights reserved.-->
<html>
<head>
<title>Berkeley DB: DbEnv::set_cachesize</title>
<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit.">
<meta name="keywords" content="embedded,database,programmatic,toolkit,b+tree,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,java,C,C++">
</head>
<body bgcolor=white>
<a name="2"><!--meow--></a>
<table><tr valign=top>
<td>
<h1>DbEnv::set_cachesize</h1>
</td>
<td width="1%">
<a href="../api_cxx/cxx_index.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a>
</td></tr></table>
<hr size=1 noshade>
<tt>
<h3><pre>
#include <db_cxx.h>
<p>
int
DbEnv::set_cachesize(u_int32_t gbytes, u_int32_t bytes, int ncache);
</pre></h3>
<h1>Description</h1>
<p>Set the size of the database's shared memory buffer pool, i.e., the cache,
to <b>gbytes</b> gigabytes plus <b>bytes</b>. The cache should be the
size of the normal working data set of the application, with some small
amount of additional memory for unusual situations. (Note, the working
set is not the same as the number of simultaneously referenced pages, and
should be quite a bit larger!)
<p>The default cache size is 256KB, and may not be specified as less than
20KB. Any cache size less than 500MB is automatically increased by 25%
to account for buffer pool overhead, cache sizes larger than 500MB are
used as specified. For information on tuning the Berkeley DB cache size, see
<a href="../ref/am_conf/cachesize.html">Selecting a cache size</a>.
<p>It is possible to specify caches to Berkeley DB that are large enough so that
they cannot be allocated contiguously on some architectures, e.g., some
releases of Solaris limit the amount of memory that may be allocated
contiguously by a process. If <b>ncache</b> is 0 or 1, the cache will
be allocated contiguously in memory. If it is greater than 1, the cache
will be broken up into <b>ncache</b> equally sized separate pieces of
memory.
<p>The DbEnv::set_cachesize interface may only be used to configure Berkeley DB before
the <a href="../api_cxx/env_open.html">DbEnv::open</a> interface is called.
<p>The DbEnv::set_cachesize method either returns a non-zero error value or throws an exception that
encapsulates a non-zero error value on failure, and returns 0 on success.
<p>The database environment's cache size may also be set using the environment's
<b>DB_CONFIG</b> file. The syntax of the entry in that file is a
single line with the string "set_cachesize", one or more whitespace characters,
and the three arguments specified to this interface, separated by whitespace
characters, for example, "set_cachesize 1 500 2". Because the <b>DB_CONFIG</b> file is read when the database
environment is opened, it will silently overrule configuration done
before that time.
<h1>Errors</h1>
<p><dl compact>
<p><dt>EINVAL<dd>An invalid flag value or parameter was specified.
<p>Called after <a href="../api_cxx/env_open.html">DbEnv::open</a> was called.
<p>The specified cache size was impossibly small.
</dl>
<h3>Class</h3>
<a href="../api_cxx/dbenv_class.html">DbEnv</a>
<h1>See Also</h1>
<a href="../api_cxx/env_close.html">DbEnv::close</a>,
<a href="../api_cxx/env_open.html">DbEnv::open</a>,
<a href="../api_cxx/env_remove.html">DbEnv::remove</a>,
<a href="../api_cxx/db_err.html">DbEnv::err</a>,
<a href="../api_cxx/env_strerror.html">DbEnv::strerror</a>,
<a href="../api_cxx/env_version.html">DbEnv::version</a>,
<a href="../api_cxx/env_set_cachesize.html">DbEnv::set_cachesize</a>,
<a href="../api_cxx/env_set_errcall.html">DbEnv::set_errcall</a>,
<a href="../api_cxx/env_set_errfile.html">DbEnv::set_errfile</a>,
<a href="../api_cxx/env_set_error_stream.html">DbEnv::set_error_stream</a>,
<a href="../api_cxx/env_set_errpfx.html">DbEnv::set_errpfx</a>,
<a href="../api_cxx/env_set_flags.html">DbEnv::set_flags</a>,
<a href="../api_cxx/env_set_mutexlocks.html">DbEnv::set_mutexlocks</a>,
<a href="../api_cxx/env_set_paniccall.html">DbEnv::set_paniccall</a>,
and
<a href="../api_cxx/env_set_verbose.html">DbEnv::set_verbose</a>.
</tt>
<table><tr><td><br></td><td width="1%">
<a href="../api_cxx/cxx_index.html"><img src="../images/api.gif" alt="API"></a><a href="../ref/toc.html"><img src="../images/ref.gif" alt="Ref"></a>
</td></tr></table>
<p><font size=1><a href="http://www.sleepycat.com">Copyright Sleepycat Software</a></font>
</body>
</html>
|
