{
  "date": "2015-04-14T10:43:20",
  "slug": "yesterdays-awr-straight-to-the-goal",
  "link": "https://www.dbi-services.com/blog/yesterdays-awr-straight-to-the-goal/",
  "title": {
    "rendered": "Yesterday&#8217;s AWR Straight to the Goal"
  },
  "content": {
    "rendered": "<h2>By Franck Pachot</h2>\n<p>.<br />\nYesterday I was a speaker at Collaborate15 and did my presentation about reading an AWR report. That was great. Many people (and not enough seats).</p>\n<p>Here are some aswers about questions that came later.</p>\n<p>I did that presentation at DOAG last year in a much bigger room. But because of the bigger room there was no questions, and because of the tension I felt in that big room, I made it too fast. Yesterday&#8217;s was better in my opinion, able to cover everything, including questions, in one hour.</p>\n<p>I was a bit surprised by the number of people having Diagnostic Pack. About 50%. This is not the case with my customers. Probably there are biggest companies in US that can affort higher licence costs.</p>\n<p>Anyway some people are in EE without Diagnostic Pack, or in SE and they run Statspack. I said that they can do exacltly the same approach as long as the take level 7 statspack reports.</p>\n<h3>Statspack level</h3>\n<p>How do you set it? Here is how to do after installing Statspack:</p>\n<pre><code>SQL&gt; exec STATSPACK.MODIFY_STATSPACK_PARAMETER (i_snap_level=&gt;7, i_modify_parameter=&gt;'true', i_instance_number=&gt;null);</code></pre>\n<p>If you are in RAC, just do the same for each instance, with the right instance number.</p>\n<p>There is a warning I always add when I give our <a href=\"index.php/products/dbi-insite-workshops/oracle-performance-tuning-training\">tuning workshop</a> : if you do it afterwards, please run one snapshot just to check there is no problem. From my experience, I have seen the following issues:</p>\n<ul>\n<li>System swapiness was configured high. The instance was quite idle, so a big part of the shared pool had been swapped. The level 7 snapshot has to read lot of cursor and execution plan information from shared pool and then the system is stuck for a while, bringing all that back in memory. The solution: configure the instance properly (swapiness=0)</li>\n<li>No automatic stats gathering were done on PERFSTAT schema. Bad statistics made the insert into STATS$SQL_PLAN very bad. Solution: gather statistics properly.</li>\n</ul>\n<p>Besides that, I don&#8217;t see know any problem having level 7 as the default. It adds segment statistics and it adds execution plan.</p>\n<h3>Predicates in explain plan</h3>\n<p>I said that predicates are missing in the plans. <a href=\"/awr-dont-store-explain-plan-predicates\">Here</a> is the reason. And &#8211; maybe &#8211; <a href=\"https://community.oracle.com/ideas/2494\">here</a> is a way to have that fixed one day. Please vote up for that idea on OTN.</p>\n<h3>Presentation material</h3>\n<p>Some people that were not at IOUG Collaborate have asked if the presentation is public. Not yet. I&#8217;ve submitted it for other events this year, so it cannot be public. But maybe you can try to drop me a mail.<br />\nPeople being there can download the pdf and white paper from <a href=\"http://coll15.mapyourshow.com/6_0/sessions/session-details.cfm?ScheduleID=3535\">here</a>.</p>\n<h3>Get deeper</h3>\n<p>You want to go further than the AWR report? You can query AWR views.<br />\nLearn that at Maris Elsins session today: <a href=\"http://coll15.mapyourshow.com/6_0/sessions/session-details.cfm?ScheduleID=3548\">Mining the AWR: Alternative Methods for Identification of the Top SQLs in Your Database</a></p>\n<h3>Conclusion</h3>\n<p>Please, don&#8217;t forget to give feedback from the Collaborate app.<br />\nThanks a lot to the attendees, as well as the IOUG Forum organisation.</p>\n<blockquote class=\"twitter-tweet\" lang=\"en\"><p>6 minutes to go and the room is already full for <a href=\"https://twitter.com/FranckPachot\">@FranckPachot</a>! Congrats <a href=\"http://t.co/jHY7n9Po0P\">pic.twitter.com/jHY7n9Po0P</a></p>\n<p>— Ludovico Caldara (@ludodba) <a href=\"https://twitter.com/ludodba/status/587758341323001857\">April 13, 2015</a></p></blockquote>\n",
    "protected": false
  }
}
