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<?xml version="1.0" encoding="utf-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xml:lang="en" lang="en" xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html;charset=utf-8" /> <meta http-equiv="Content-Style-Type" content="text/css" /> <!-- MOTW-DISABLED saved from url=(0014)about:internet --> <title>Indexes</title> <link rel="StyleSheet" href="css/btrieve.css" type="text/css" media="all" /> <link rel="StyleSheet" href="css/webworks.css" type="text/css" media="all" /> <script type="text/javascript" language="JavaScript1.2" src="wwhdata/common/context.js"></script> <script type="text/javascript" language="JavaScript1.2" src="wwhdata/common/towwhdir.js"></script> <script type="text/javascript" language="JavaScript1.2" src="wwhdata/common/wwhpagef.js"></script> <script type="text/javascript" language="JavaScript1.2"> <!-- var WebWorksRootPath = ""; // --> </script> <script type="text/javascript" language="JavaScript1.2"> <!-- // Set reference to top level help frame // var WWHFrame = WWHGetWWHFrame("", true); // --> </script> <script type="text/javascript" language="JavaScript1.2" src="scripts/expand.js"></script> </head> <body class="" style="background-color: #FFFFEE;" onload="WWHUpdate();" onunload="WWHUnload();" onkeydown="WWHHandleKeyDown((document.all||document.getElementById||document.layers)?event:null);" onkeypress="WWHHandleKeyPress((document.all||document.getElementById||document.layers)?event:null);" onkeyup="WWHHandleKeyUp((document.all||document.getElementById||document.layers)?event:null);"> <br /> <div class="WebWorks_Breadcrumbs" style="text-align: left;"> <a class="WebWorks_Breadcrumb_Link" href="btrieve.20.01.html#106668">15 The Btrieve (Pervasive.SQL) Driver</a> : Indexes</div> <hr align="left" /> <blockquote> <div class="head_1"><a name="106668">Indexes</a></div> <div class="Body"><a name="106669">NOTE: If you define an index using the Btrieve driver, the index will not have the restrictions </a>discussed here.</div> <div class="Body"><a name="106670">For query optimization, the Btrieve driver does not use the following:</a></div> <div class="list_bulleted_outer" style="margin-left: 0pt;"> <table border="0" cellspacing="0" cellpadding="0" summary=""> <tr style="vertical-align: baseline;"> <td> <div class="list_bulleted_inner" style="width: 18pt; white-space: nowrap;">â? </div> </td> <td width="100%"> <div class="list_bulleted_inner"><a name="106671">Indexes containing all-segment-null keys or any-segment-null keys.</a></div> </td> </tr> </table> </div> <div class="list_bulleted_outer" style="margin-left: 0pt;"> <table border="0" cellspacing="0" cellpadding="0" summary=""> <tr style="vertical-align: baseline;"> <td> <div class="list_bulleted_inner" style="width: 18pt; white-space: nowrap;">â? </div> </td> <td width="100%"> <div class="list_bulleted_inner"><a name="106672">Any index key that is marked case-insensitive.</a></div> </td> </tr> </table> </div> <div class="list_bulleted_outer" style="margin-left: 0pt;"> <table border="0" cellspacing="0" cellpadding="0" summary=""> <tr style="vertical-align: baseline;"> <td> <div class="list_bulleted_inner" style="width: 18pt; white-space: nowrap;">â? </div> </td> <td width="100%"> <div class="list_bulleted_inner"><a name="106673">Any index keys where the data type of the index key does not match the data type of the </a>field. The one exception is if the index key is declared as an unsigned integer and the field in the file is declared as signed integer, or vice versa, then the driver assumes the field contains only unsigned quantities and uses the index. Note that this can lead to incorrect results if the field in fact does contain signed quantities.</div> </td> </tr> </table> </div> <div class="Body"><a name="106674">The Btrieve driver only uses an alternate-collating-sequence (ASC) index key for equality </a>lookups. Additionally, if an ASC key is part of a segmented index, the other index segments are not used for query optimization unless the Where clause contains an equality condition for the ASC key.</div> <script type="text/javascript" language="JavaScript1.2"> <!-- // Clear related topics // WWHClearRelatedTopics(); document.writeln(WWHRelatedTopicsInlineHTML()); // --> </script> </blockquote> <script type="text/javascript" language="JavaScript1.2"> <!-- document.write(WWHRelatedTopicsDivTag() + WWHPopupDivTag() + WWHALinksDivTag()); // --> </script> </body> </html>
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