<?xml version="1.0" encoding="utf-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns:MadCap="http://www.madcapsoftware.com/Schemas/MadCap.xsd" MadCap:lastBlockDepth="2" MadCap:lastHeight="120" MadCap:lastWidth="624" MadCap:disableMasterStylesheet="true" MadCap:tocPath="Basics Operations & Concepts|Indexing" MadCap:InPreviewMode="false" MadCap:RuntimeFileType="Topic" MadCap:TargetType="WebHelp" MadCap:PathToHelpSystem="../../../" MadCap:HelpSystemFileName="index.xml" MadCap:SearchType="Stem"> <head><title>Costs And Benefits</title> <script type="text/javascript">/* <![CDATA[ */ window.onload = function(){ var pathToFlash = $('html').attr('MadCap:PathToHelpSystem') + 'Content/Resources/Code/ZeroClipboard.swf'; ZeroClipboard.setMoviePath(pathToFlash); function bindToClipBord(element,content){ var clip = new ZeroClipboard.Client(); clip.setText(content); clip.glue(element); }; if(location.protocol==='file:'){ $('.copylink-marker').remove(); } else{ $('.copylink-marker').each(function(){ var text = $(this).parent().parent().children('.prettyprint').html(); $(this).hover(function(){ bindToClipBord(this,text); }, function(){}); }); } prettyPrint(); }; /* ]]> */</script> <link href="../../SkinSupport/MadCap.css" rel="stylesheet" /> <link href="../../Resources/Stylesheets/OnlineStyle.css" rel="stylesheet" /> <script src="../../Resources/Code/prettify.js"> </script> <script src="../../Resources/Code/lang-vb.js"> </script> <script src="../../Resources/Code/jquery.min.js"> </script> <script src="../../Resources/Code/ZeroClipboard.js"> </script> <script src="../../SkinSupport/MadCapAll.js" type="text/javascript"> </script> </head> <body> <p class="MCWebHelpFramesetLink" style="display: none;"><a href="../../../index_CSH.html#basics/indexing/costs_and_benefits.htm" style="">Open topic with navigation</a> </p> <div class="MCBreadcrumbsBox"><span class="MCBreadcrumbsPrefix">You are here: </span><a class="MCBreadcrumbsLink" href="../../basics.htm">Basics Operations & Concepts</a><span class="MCBreadcrumbsDivider"> > </span><a class="MCBreadcrumbsLink" href="../indexing.htm">Indexing</a><span class="MCBreadcrumbsDivider"> > </span><span class="MCBreadcrumbs">Costs And Benefits</span> </div> <p> <script type="text/javascript">/*<![CDATA[*/document.write('<a href="' + location.href +'">'); document.write("Direct Link"); document.write('</a>');/*]]>*/</script> </p> <p> </p> <h1>Costs And Benefits</h1> <p>Maintaining an index is additional work and therefore it has its costs. Each time you store a objects which has an index on it, db4o needs to look up the a appropriate place in the index and store a entry there. This costs is paid for each store, update or delete operation. Therefore there's a tradeoff when adding indexes.</p> <p>The costs are mostly the time consumed to maintain the index. Additionally there's some additional space consumed to store the index. The benefits is that queries which run a order of magnitude faster when using an index.</p> <p>In practice you should measure and benchmark your solution and check if a index is a benefit to your application. Ensure that you have enough test data. The influence of indexes shows better with a lot of objects. (10'000 and more objects). However since most applications do a lot more read operations than store and update operations adding a index brings a huge benefit.</p> <script type="text/javascript" src="../../SkinSupport/MadCapBodyEnd.js"> </script> </body> </html>