<!--$Id: db_set_h_nelem.so,v 10.33 2003/11/08 19:17:21 bostic Exp $--> <!--Copyright 1997-2003 by Sleepycat Software, Inc.--> <!--All rights reserved.--> <!--See the file LICENSE for redistribution information.--> <html> <head> <title>Berkeley DB: DB->set_h_nelem</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 width="100%"><tr valign=top> <td> <h3>DB->set_h_nelem</h3> </td> <td align=right> <a href="../../db42-devel-4.2.52/api_c/api_index.html"><img src="../../db42-4.2.52/images/api.gif" alt="API"></a> <a href="../../db42-devel-4.2.52/ref/toc.html"><img src="../../db42-4.2.52/images/ref.gif" alt="Ref"></a> </td></tr></table> <hr size=1 noshade> <tt> <h3><pre> #include <db.h> <p> int DB->set_h_nelem(DB *db, u_int32_t h_nelem); <p> int DB->get_h_nelem(DB *db, u_int32_t *h_nelemp); </pre></h3> <hr size=1 noshade> <h3>Description: DB->set_h_nelem</h3> <a name="3"><!--meow--></a> <p>Set an estimate of the final size of the hash table.</p> <p>In order for the estimate to be used when creating the database, the <a href="../../db42-devel-4.2.52/api_c/db_set_h_ffactor.html">DB->set_h_ffactor</a> method must also be called. If the estimate or fill factor are not set or are set too low, hash tables will still expand gracefully as keys are entered, although a slight performance degradation may be noticed.</p> <p>The DB->set_h_nelem method configures a database, not only operations performed using the specified <a href="../../db42-devel-4.2.52/api_c/db_class.html">DB</a> handle.</p> <p>The DB->set_h_nelem method may not be called after the <a href="../../db42-devel-4.2.52/api_c/db_open.html">DB->open</a> method is called. If the database already exists when <a href="../../db42-devel-4.2.52/api_c/db_open.html">DB->open</a> is called, the information specified to DB->set_h_nelem will be ignored. </p> <p>The DB->set_h_nelem method returns a non-zero error value on failure and 0 on success. </p> <h3>Parameters</h3> <p><dl compact> <p><dt><b>h_nelem</b><dd> The <b>h_nelem</b> parameter is an estimate of the final size of the hash table. </dl> <h3>Errors</h3> <p>The DB->set_h_nelem method may fail and return one of the following non-zero errors:</p> <p><dl compact> <p><dt>EINVAL<dd>If the method was called after <a href="../../db42-devel-4.2.52/api_c/db_open.html">DB->open</a> was called; or if an invalid flag value or parameter was specified. </dl> <hr size=1 noshade> <h3>Description: DB->get_h_nelem</h3> <p>The DB->get_h_nelem method returns the estimate of the final size of the hash table.</p> <p>The DB->get_h_nelem method may be called at any time during the life of the application.</p> <p>The DB->get_h_nelem method returns a non-zero error value on failure and 0 on success. </p> <h3>Parameters</h3> <p><dl compact> <p><dt><b>h_nelemp</b><dd> The DB->get_h_nelem method returns the estimate of the final size of the hash table in <b>h_nelemp</b>. </dl> <hr size=1 noshade> <h3>Class</h3> <a href="../../db42-devel-4.2.52/api_c/db_class.html">DB</a> <h3>See Also</h3> <a href="../../db42-devel-4.2.52/api_c/db_list.html">Databases and Related Methods</a> </tt> <table width="100%"><tr><td><br></td><td align=right> <a href="../../db42-devel-4.2.52/api_c/api_index.html"><img src="../../db42-4.2.52/images/api.gif" alt="API"></a><a href="../../db42-devel-4.2.52/ref/toc.html"><img src="../../db42-4.2.52/images/ref.gif" alt="Ref"></a> </td></tr></table> <p><font size=1><a href="../../db42-devel-4.2.52/sleepycat/legal.html">Copyright (c) 1996-2003</a> <a href="http://www.sleepycat.com">Sleepycat Software, Inc.</a> - All rights reserved.</font> </body> </html>