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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=us-ascii" /> <meta http-equiv="Content-Style-Type" content="text/css" /> <meta http-equiv="Content-Script-Type" content="text/javascript" /> <title>Active Session History Statistics</title> <meta name="generator" content="Oracle DARB XHTML Converter (Mode = ohj/ohw) - Version 5.1.1 Build 005" /> <meta name="date" content="2009-05-27T15:13:1Z" /> <meta name="robots" content="noarchive" /> <meta name="doctitle" content="Active Session History Statistics" /> <meta name="relnum" content="11g Release 2 (11.2)" /> <meta name="partnum" content="E10822-01" /> <link rel="copyright" href="./dcommon/html/cpyr.htm" title="Copyright" type="text/html" /> <link rel="stylesheet" href="./dcommon/css/blafdoc.css" title="Oracle BLAFDoc" type="text/css" /> <link rel="contents" href="toc.htm" title="Contents" type="text/html" /> <link rel="prev" href="tdppt_method004.htm" title="Previous" type="text/html" /> <link rel="next" href="tdppt_method006.htm" title="Next" type="text/html" /> <script src="./callback.js" type="text/javascript"></script> <noscript>Your browser does not support JavaScript. This help page requires JavaScript to render correctly.</noscript> </head> <body> <div class="zz-skip-header"><a href="#BEGIN">Skip Headers</a></div> <table class="simple oac_no_warn" summary="" cellspacing="0" cellpadding="0" width="100%"> <col width="86%" /> <col width="*" /> <tr valign="bottom"> <td align="left"></td> <td align="center"><a href="tdppt_method004.htm"><img src="./dcommon/gifs/leftnav.gif" alt="Previous" /><br /> <span class="icon">Previous</span></a> </td> <td align="center"><a href="tdppt_method006.htm"><img src="./dcommon/gifs/rightnav.gif" alt="Next" /><br /> <span class="icon">Next</span></a></td> </tr> </table> <p><a id="CIHBEFGH" name="CIHBEFGH"></a><a id="TDPPT011" name="TDPPT011"></a></p> <div class="sect2"><!-- infolevel="all" infotype="General" --> <h1>Active Session History Statistics</h1> <a name="BEGIN" id="BEGIN"></a> <p>The Active Session History<a id="sthref24" name="sthref24"></a><a id="sthref25" name="sthref25"></a> (ASH) statistics are samples of session activity in the database. The database samples active sessions every second and stores them in a circular buffer in the System Global Area (SGA). Any session that is connected to the database and using CPU, or is waiting for an event that does not belong to the idle wait class, is considered an active session. By capturing only active sessions, a manageable set of data is represented. The size of the data is directly related to the work being performed, rather than the number of sessions allowed on the system.</p> <p>Using the DB time example described in <a href="tdppt_method002.htm#CIHCACJG">"Time Model Statistics"</a>, samples of session activity are collected from the online transaction made at the bookseller's Web site, represented as vertical lines below the horizontal arrow in <a href="#CIHBAFGI">Figure: Active Session History</a>.</p> <div class="figure"><a id="CIHBAFGI" name="CIHBAFGI"></a><a id="TDPPT347" name="TDPPT347"></a> <p class="titleinfigure">Active Session History</p> <img src="./tdppt003.gif" alt="Description of this figure follows" title="Description of this figure follows" longdesc="./img_text/tdppt003.htm" /><br /> <a id="sthref26" name="sthref26" href="./img_text/tdppt003.htm">Description of "Active Session History"</a><br /> <br /></div> <!-- class="figure" --> <p>The light vertical lines represent samples of inactive session activity that are not captured in the ASH statistics. The bold vertical lines represent samples of active sessions that are captured at:</p> <ul> <li> <p>7:38, while novels by the author are being queried</p> </li> <li> <p>7:42, while the user is browsing the query results</p> </li> <li> <p>7:50, when one of the novels is added to the shopping cart</p> </li> <li> <p>7:52, during the checkout process</p> </li> </ul> <p><a href="#CIHDGJAH">Table: Active Session History</a> lists ASH statistics collected for the active sessions, along with examples of the session ID (SID), module, SQL ID, session state, and wait events that are sampled.</p> <div class="tblformal"><a id="TDPPT348" name="TDPPT348"></a><a id="sthref27" name="sthref27"></a><a id="CIHDGJAH" name="CIHDGJAH"></a> <p class="titleintable">Active Session History</p> <table class="Formal" title="Active Session History" summary="4 ASH samplings are listed with values for time, SID, module, SQL ID, state, and event" dir="ltr" border="1" width="100%" frame="hsides" rules="groups" cellpadding="3" cellspacing="0"> <col width="7%" /> <col width="7%" /> <col width="24%" /> <col width="23%" /> <col width="14%" /> <col width="*" /> <thead> <tr align="left" valign="top"> <th align="left" valign="bottom" id="r1c1-t8">Time</th> <th align="left" valign="bottom" id="r1c2-t8">SID</th> <th align="left" valign="bottom" id="r1c3-t8">Module</th> <th align="left" valign="bottom" id="r1c4-t8">SQL ID</th> <th align="left" valign="bottom" id="r1c5-t8">State</th> <th align="left" valign="bottom" id="r1c6-t8">Event</th> </tr> </thead> <tbody> <tr align="left" valign="top"> <td align="left" id="r2c1-t8" headers="r1c1-t8"> <p>7:38</p> </td> <td align="left" headers="r2c1-t8 r1c2-t8"> <p>213</p> </td> <td align="left" headers="r2c1-t8 r1c3-t8"> <p>Book by author</p> </td> <td align="left" headers="r2c1-t8 r1c4-t8"> <p>qa324jffritcf</p> </td> <td align="left" headers="r2c1-t8 r1c5-t8"> <p>Waiting</p> </td> <td align="left" headers="r2c1-t8 r1c6-t8"> <p>db file sequential read</p> </td> </tr> <tr align="left" valign="top"> <td align="left" id="r3c1-t8" headers="r1c1-t8"> <p>7:42</p> </td> <td align="left" headers="r3c1-t8 r1c2-t8"> <p>213</p> </td> <td align="left" headers="r3c1-t8 r1c3-t8"> <p>Get review ID</p> </td> <td align="left" headers="r3c1-t8 r1c4-t8"> <p>aferv5desfzs5</p> </td> <td align="left" headers="r3c1-t8 r1c5-t8"> <p>CPU</p> </td> <td align="left" headers="r3c1-t8 r1c6-t8"> <p>n/a</p> </td> </tr> <tr align="left" valign="top"> <td align="left" id="r4c1-t8" headers="r1c1-t8"> <p>7:50</p> </td> <td align="left" headers="r4c1-t8 r1c2-t8"> <p>213</p> </td> <td align="left" headers="r4c1-t8 r1c3-t8"> <p>Add item to cart</p> </td> <td align="left" headers="r4c1-t8 r1c4-t8"> <p>hk32pekfcbdfr</p> </td> <td align="left" headers="r4c1-t8 r1c5-t8"> <p>Waiting</p> </td> <td align="left" headers="r4c1-t8 r1c6-t8"> <p>buffer busy wait</p> </td> </tr> <tr align="left" valign="top"> <td align="left" id="r5c1-t8" headers="r1c1-t8"> <p>7:52</p> </td> <td align="left" headers="r5c1-t8 r1c2-t8"> <p>213</p> </td> <td align="left" headers="r5c1-t8 r1c3-t8"> <p>Checkout</p> </td> <td align="left" headers="r5c1-t8 r1c4-t8"> <p>abngldf95f4de</p> </td> <td align="left" headers="r5c1-t8 r1c5-t8"> <p>Waiting</p> </td> <td align="left" headers="r5c1-t8 r1c6-t8"> <p>log file sync</p> </td> </tr> </tbody> </table> <br /></div> <!-- class="tblformal" --> <div class="helpinfonotealso"> <h2>Related Topics</h2> <p><a href="tdppt_method001.htm#CAEICJEI">Gathering Database Statistics Using the Automatic Workload Repository</a></p> </div> </div> <!-- class="sect2" --> <!-- Start Footer --> <div class="footer"> <table class="simple oac_no_warn" summary="" cellspacing="0" cellpadding="0" width="100%"> <col width="86%" /> <col width="*" /> <tr> <td align="left"><span class="copyrightlogo">Copyright © 2007, 2009, Oracle and/or its affiliates. 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