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Oracle database performance
Updated: 5 days 13 hours ago

Another python graph – one wait event

Thu, 2016-01-14 17:28

Here is another graph that I created in Python with Pyplot:


This is on my github repository. has the plotting code. has the query. has the database access code.

I blanked out the database name in the example graph to hide it.

This is a graphical version of my onewaitevent.sql script. It queries the AWR looking at a particular wait event per hour. You look at the number of wait events in an hour to see how busy the system was and then the average elapsed time for that hour. Also, you set the smallest number of waits to include so you can drop hours where nothing is going on.

In the example graph you can find times where the average time for a db file sequential read is high and the system is busy. You use the top graph to see how busy the system is and the bottom to see where the average time spikes.

Still just an experiment but I thought I would pass it along. It isn’t that hard to create the graph in Python and I seem to have a lot of flexibility since I’m writing code instead of using an existing program like Excel.



Categories: DBA Blogs

Trying Python and Pyplot for Database Performance Graphs

Wed, 2016-01-06 16:16

In the past I have used Excel to graph things related to Oracle database performance. I am trying out Python and the Pyplot library as an alternative to Excel.  I took a graph that I had done in Excel and rewrote it in Python. The graph shows the CPU usage within the database by category.  For example, I labeled the database CPU used by a group of web servers “WEBFARM1” on the graph.

Here is an example graph:


You can find most of this code in the Python section of my GitHub repository. Here is the code that I used to create the example graph above using some made up data: zip

To make this graph in Excel I was running a sqlplus script and cutting and pasting the output into a text file that I imported into Excel. Very manual. No doubt there are ways that I could have automated what I was doing in Excel. But I have studied Python as part of the edX classes I took so I thought I would give it a try.

Python let me write a program to run the graph from an icon on my desktop. I used the cx_Oracle package to pull the data from the database and Pyplot for the graph.

I’m running the Windows 32 bit version of Canopy Express for my Python development environment. This environment comes with Pylot so I just had to install cx_Oracle to have all the packages I needed to make the graph.

I think both Excel and Python/Pyplot still have value. Excel still seems easier for quick and dirty graphing. But I used Python to automate a report that I run every day with fewer manual steps.  Probably could have done the same thing in Excel but I have recently studied Python so I was able to apply what I learned in my classes without a lot more effort.




Categories: DBA Blogs

Github Repository

Tue, 2015-12-22 10:33

I am experimenting with Github. I have created a repository for my Oracle database related scripts. Here is my Github URL:

You can clone this repository locally if you have git installed using this command:

git clone

I’ve had challenges before when I write a blog post about a script and then revise the script later.  It seems weird to update the post with links to the new version.  So, I’m thinking of using github to expose the scripts that I want to share with the Oracle community and then I can update them over time and the version history will be visible.

Let me know if you have any questions or suggestions.  This is just my first attempt at using Github for this purpose.


Categories: DBA Blogs

Update hinted for wrong index

Fri, 2015-11-13 10:52

I worked with our support team to improve the performance of a PeopleSoft Financials update statement yesterday. The update statement had an index hint already in it but the index was not the best one of the available indexes.

Here is the original update statement:

 BANK_CD = :2,

I listed out the columns for the indexes on the table using the “querytuning” part of my standard sql tuning scripts.

Here are the columns for the hinted index:


The where clause includes only the first two columns.

But another similar index, PSEPYMNT_VCHR_XREF, exists with these columns:


The where clause has all three of these columns. So, why was the original query hinted this way? Does the E index not work better than the C index? I ran this query to see how selective the condition PYMNT_SELCT_STATUS = ‘N’ is.

>select PYMNT_SELCT_STATUS,count(*)
 4 AND B.REMIT_VENDOR = '12345678'

- ----------
C 5
N 979
P 177343
X 5485

I included the conditions on the first two columns that both indexes share, but removed the other conditions from the original update. A count on the number of rows that meet the conditions of only these two columns shows how many rows the original index will have to use to check the remaining where clause conditions.

I grouped by PYMNT_SELCT_STATUS to see how many rows met the condition PYMNT_SELCT_STATUS = ‘N’ and how many did not. Grouping on PYMNT_SELCT_STATUS shows how many rows the new index will use to check the remaining conditions in the where clause. I ran this query to see if the second index would use fewer rows than the first.

This query showed that only 979 of the over 180,000 rows met the condition. This made me think that the E index which includes PYMNT_SELCT_STATUS has a good chance of speeding up the original update. I ran a count with a hint forcing the C index and then again forcing the E index:

>set timing on
>select /*+ INDEX(B PSCPYMNT_VCHR_XREF) */ count(*)
 4 AND B.REMIT_VENDOR = '12345678'
 6 AND B.PYMNT_ID = ' '


Elapsed: 00:13:52.53
>select /*+ INDEX(B PSEPYMNT_VCHR_XREF) */ count(*)
 4 AND B.REMIT_VENDOR = '12345678'
 6 AND B.PYMNT_ID = ' '


Elapsed: 00:00:01.28

The original hint caused the select count(*) query to run in 13 minutes while the new hint caused it to run in 1 second. Clearly the new E index causes the query to run faster!

The developer that I was working with found the problem update statement in some PeopleCode and was able to edit the hint forcing it to use the better index. We migrated the modified code to production and the user was able to run the update statement without the web site timing out. Prior to the change the user was not able to complete the update because the SQL statement took so long it exceeded our application server timeout.



Categories: DBA Blogs

Tested 1000 Select Statements on New Exadata X5

Fri, 2015-11-06 17:37

I finished testing 1000 select statements on our new Exadata X5 to see if they would run faster or slower than on our older Exadata V2.  Our current production V2 has 12 nodes and the new X5 has only 2.  The memory and parallel server parameters on the X5 are 6 times are large as on the old one, since we have one sixth as many hosts and more than 6 times the memory and CPU per host. I think that memory parameters can sometimes change execution plans, and of course with the newer Exadata software who knows what other differences we might see.  I wanted to see if any plan changes or other issues caused some queries to run much slower on our newer Exadata system than the old one. I picked 1000 select statements at random from our current production and tested them comparing plans and execution time. In the end I did not find any bad plan changes and on average the tested select statements ran about 4 times faster on the X5 than on the older V2.

I used my testselect package that I have mentioned in several other posts. Here are some other examples of using this package for performance tuning:

In the other posts I was using the package to test the effect of some change on query plans and performance.  So, I was comparing two different situations on the same host. But, in this case I was comparing two different hosts with essentially the same data and settings. But they had different versions of Exadata hardware and larger parameters and fewer nodes on the newer host.  Here are the results of my first run with all 1000 statements.  I got the execution plan for all 1000 select statements but only executed the ones with different plans.  Here were the results:

>execute TEST_SELECT.display_results('X5','V2');
Select statements that ran 3 times faster with X5 than with V2.
        --------- -------------------- -------------------- --------------------- ---------------------
                3            287237826            287237826                     3                    34
                4           1245040971           1245040971                     1                    11
                9             36705296           2770058206                     4                    22

... edited out most of the lines for brevity ...

              997           2423577330           2423577330                     0                     9
              998           2217180459           3921538090                     1                    13
             1000           3842377551           1690646521                     2                    12
Number of selects=329
Select statements that ran 3 times faster with V2 than with X5.
        --------- -------------------- -------------------- --------------------- ---------------------
               95           3919277442           3919277442                     0                     2
              210           3508255766           3508255766                     0                     2
              282           3946849555           3085057493                     0                     6
              347           3278587008            789099618                    19                   170
              375            581067860            460184496                     0                     3
              429            534521834            534521834                     1                     6
              569           3953904703           3484839332                     0                     2
              681            946688683           3451337204                     1                     6
              697            908111030           2971368043                     0                     1
              699           3756954097           1915145267                     0                     1
              706           1121196591           1121196591                     0                     2
              708            581067860            460184496                     0                     4
              797            908111030           2841065272                     0                     5
              950            786005624           2571241212                    45                   460
              966           3151548044           3151548044                     1                     5
Number of selects=15
Summary of test results
        -------------------- ------------------------ ---------------- --------------------------
                          X5 5545.9999999999999999999              486                         11
                          V2                    21138              486                         43

Of the tested statements 329 ran 3 or more times faster on the X5.  But 15 selects ran 3 or more times faster on the old V2.  So, I needed to test the 15 selects again on both servers.

I’m not sure if it was smart or not, but I decided to run all the selects 5 times in a row to maximize caching.  The X5 is new and not in use so there wouldn’t be any activity to stimulate caching.  My test script for the X5 looked like this:

truncate table test_results;

execute TEST_SELECT.execute_all('X5');
execute TEST_SELECT.execute_all('X5');
execute TEST_SELECT.execute_all('X5');
execute TEST_SELECT.execute_all('X5');
execute TEST_SELECT.execute_all('X5');
execute TEST_SELECT.reexecute_errored('X5');
execute TEST_SELECT.reexecute_errored('X5');
execute TEST_SELECT.reexecute_errored('X5');
execute TEST_SELECT.reexecute_errored('X5');
execute TEST_SELECT.reexecute_errored('X5');

After we made sure that the system had cached everything, all 15 selects ran, on average, 4 times faster on the X5 than the V2:

-- ---------- ------------- ----------------- ----------------- ------------ ------------------ ------------------------ --------------- ------------- ------------------ -------------- ----------------------------------------------------------------
X5         95 54a8k0yhbgyfq                          3919277442            1                  0                       12            2583            14                  0              1
V2         95 54a8k0yhbgyfq                          3919277442            1                  1                       15            2583            14                  1              1
V2        210 b132ygmp743h4                          3508255766            0                  2                       19            1592            14                  0              1
X5        210 b132ygmp743h4                          3508255766            0                  2                        8            1430            14                  0              1
V2        282 aw5f12xsa8c2h                          3946849555            0                  0                       14            3468            14                  0              2
X5        282 aw5f12xsa8c2h                          3946849555            0                  0                        8            3322            14                  2              2
V2        347 8ncbyjttnq0sk                          3278587008            1                  3                      462         1203794            14                  0          61838
X5        347 8ncbyjttnq0sk                          3278587008            1                  2                      206         1126539            14                  4          51849
X5        375 4yq5jkmz2khv5                           581067860            0                  0                        9           14530            14                  0              2
V2        375 4yq5jkmz2khv5                           581067860            0                  0                       19           14686            14                  1              2
V2        429 49pyzgr4swm4p                           534521834            0                  2                       11            1814            14                  0              0
X5        429 49pyzgr4swm4p                           534521834            0                  0                        5            1638            14                  1              0
X5        569 3afmdkmzx6fw8                           630418386          694                  0                       74           70173            14                  3              0
V2        569 3afmdkmzx6fw8                          3527323087          694                  1                       73           68349            14                  0           3588
V2        681 dyufm9tukaqbz                           668513927            0                  0                       10            6298            14                  0              2
X5        681 dyufm9tukaqbz                          3317934314            0                  0                        8            6096            14                  0              2
V2        697 1fqc3xkzw8bhk                           908111030            0                  0                        3            1406            14                  0              1
X5        697 1fqc3xkzw8bhk                           908111030            0                  0                        2            1406            14                  0              1
V2        699 03qk2cjgr4q2k                          1915145267           31                  0                      476           95922            14                  1              0
X5        699 03qk2cjgr4q2k                          1915145267           31                  0                      272           96299            14                  0              0
V2        706 28fnjtdhjqwrg                          1121196591            0                  0                       21            1355            14                  0              4
X5        706 28fnjtdhjqwrg                          1121196591            0                  0                       13            1355            14                  0              4
V2        708 2yrkwqs46nju0                           581067860            0                  0                       14           14684            14                  0              0
X5        708 2yrkwqs46nju0                           581067860            0                  0                        9           14528            14                  0              0
V2        797 dc5481yn8pm85                           908111030            0                  0                        3            1407            14                  0              2
X5        797 dc5481yn8pm85                           908111030            0                  0                        2            1407            14                  0              2
V2        950 by6n1m74j82rt                           786005624            6                  7                     2087          249736            14                  1         245443
X5        950 by6n1m74j82rt                          2571241212            6                  0                      186           90897            14                  0              3
X5        966 5c2n74gfrxwxx                          3151548044           12                  0                       24          116360            14                  9          84949
V2        966 5c2n74gfrxwxx                          3151548044           12                  0                       52          119701            14                  1          88002

The summary of the results:

Select statements that ran 3 times faster with X5 than with V2.
	--------- -------------------- -------------------- --------------------- ---------------------
	       95           3919277442           3919277442                     0                     1
	      429            534521834            534521834                     0                     2
	      569            630418386           3527323087                     0                     1
	      950           2571241212            786005624                     0                     7
Number of selects=4
Select statements that ran 3 times faster with V2 than with X5.
	--------- -------------------- -------------------- --------------------- ---------------------
Number of selects=0
Summary of test results
	-------------------- ------------------------ ---------------- --------------------------
	                  X5                        4               15                          0
	                  V2                       16               15                          1

I guess it is no surprise that the X5 is faster than the five-year older V2.  But, I thought it was a good example of how to use my testselect package to do see how a set of queries will run in two different situations.


Categories: DBA Blogs

OakTable video of myself and others

Tue, 2015-11-03 10:53

You can find the full length video of my Delphix talk that I did at OakTable World on Tuesday here: url

Also, the OakTable folks have updated the OakTable World agenda page with video of all the talks. This has lots of good material and for free. Scroll down to the bottom of the page to find the links to the videos.


Categories: DBA Blogs

Final day – OpenWorld and Delphix Sync

Thu, 2015-10-29 20:54

This morning was my last day of Oracle OpenWorld sessions and this afternoon and evening finished off my day with Delphix Sync.

The first talk was my only NoSQL talk. It was interesting because the claim was that NoSQL was good for large numbers of simple transactions. This seems to be a theme across a couple of sessions. The funny thing is that the NoSQL code reminded me of my pre-SQL mainframe Datacom DB database programming days. You specified the table and the index and fetched rows etc. You are the optimizer! Of course, you can do the same with simple one table queries in SQL. But, Oracle’s NoSQL may have some concurrency modes that Oracle’s main RDBMS doesn’t have for what that’s worth. The fun thing was that they had examples using Python and I’ve taken Python on Edx so I could read the code. Also, they talked about the REST API and I had done a few REST commands with JSON working through a demo of the Oracle database cloud a few weeks back. So, there were synergies with things I already know.

Next I went to this packed session by someone from Tumbler describing their approach to sharding and scaling. The two packed sessions I went to this week were both MySQL sessions and both by internet companies – Tumbler and Ticketmaster. They were in kind of small rooms and it was a little warm and stuffy. But, I found both very interesting. Supporting large web apps is a pretty cool proposition. Something that in another life would be fun to work on.

Next I went to a PeopleSoft session. I’ve done PeopleSoft for 20 years and I’m bored with it but I figure I should keep up with the latest. It was actually more of a functional presentation on modules that I have never used so most of the information was of no use to me. But, the new Fluid User Interface that I had never seen before interested me so I stayed long enough to get a feel for it. It seems that Oracle built it for tablets and maybe smart phones.

Next it was off to the hip (or should I say hipster :)) Hotel Zetta for Delphix Sync. It was a very cool event with a fun venue and lots of good snacks. No dinner for me tonight. I got a chance to do a ten minutes lightning talk that I built from three slides from Tuesday’s presentation. I got positive feedback but I felt kind of intimidated by all the Delphix techies. There were a lot of Delphix leaders and developers present as well as a number of people from larger customers. I heard a great talk on Delphix performance and other customers and Delphix employees spoke as well. I learned a lot and it makes me think I need to delve back into our Delphix environment and give it a thorough check out.

So, my OpenWorld/Delphix Sync week is over and I am beat. Like always these conferences leave me with information overload. I’m back to the prioritization thing that always dogs my step. There is just too much to learn and do. Where do I put my time? We shall see.


Categories: DBA Blogs

Wednesday OpenWorld

Wed, 2015-10-28 21:27

Well, it was a long day but it ended in a fun way.

Today I was back to the normal OpenWorld sessions starting with the general session. It was eye-opening because the speakers described a new CPU chip that they were using in their latest servers.  It had some custom elements to support database processing.  It was strange because I have recently been studying the latest Intel x86 documentation and it was interesting to compare Intel’s chips with the latest Sun/Oracle chip.  I had read about the specialized SIMD instructions in the x86 family that Intel uses to speed up graphics. So, I was not surprised that Oracle is including more complex additions to their new chip with specialized instructions.  Still, I question whether people are really going to buy anything but Intel x86 at this point due to the price/performance.

Next I went to a session describing the way a company used a tool called Chef to manage their Weblogic deployments.  The session topic interested me because we also use Weblogic at US Foods.  But it was a little hard to follow.  Maybe it would have helped if I had been exposed to Chef before hearing the talk. Still, it was good to know that there are tools out there to help automate deployment of new systems.

Next I caught a PeopleSoft in the Cloud talk. It seems that you will install the latest version of PeopleTools in a very different way than you did in the past.  I got the feeling that this was just a part way step toward fully setting up PeopleSoft to run in the cloud.

Then I went to a really cool talk about how Ticketmaster sells 20,000 tickets in one minute. It was about their MySQL architecture.  They have a large farm of MySQL servers supporting the queries behind their ticketing web site.  But, they use Oracle for the updates related to ticket purchases.

Then I went to a talk on Oracle ZFS.  I get the feeling that I need to learn more about ZFS. It seems that ZFS is an ancestor of Delphix and I know that there is a free OpenZFS that I might play with. I think that Tim Gorman, who works for Delphix, mentioned something about OpenZFS  at his Ted talk at Oak Table World Tuesday so there may be some relationship.

Lastly I went to a talk about how you can use Oracle’s Enterprise Manager to support both on site and cloud databases.  It sounds good but I think it still need to mature over time to support the cloud systems more fully.

Then at 5:30 pm I went to a fun bloggers party sponsored by Pythian and the Oracle Technology Network (OTN).  I’m not a big party person but I had a good time.  It was easy to strike up a conversation with people since we had a lot in common.

Anyway, enough for today.  One more day Thursday and then my brain will overflow. :)


Categories: DBA Blogs

Tuesday OakTable World – brain fried!

Tue, 2015-10-27 19:08

Instead of going to the normal OpenWorld events today I went to OakTable World.  Now my brain is fried from information overload. :)

It started at 8 am with a nice talk about hash joins and Bloom filters.  Toon Koppelaars had some nice moving graphics showing how bloom filters work.  I’ve studied Bloom filters before but I’m not sure I understood it with the clarity that I had after this talk.

Then I did my talk at 9 am.  The best part for me was that we had a number of questions.  I ended up skipping several slides because of time but I felt like we helped people get what they wanted out of it by having the questions and discussion.  In retrospect my talk could have used more of an introduction to Delphix itself for this audience but I think we covered the essentials in the end.

Next Kellyn Pot’Vin-Gorman did more of a community service type of talk which was a change of pace.  She had a Raspberry Pi project which was a stuffed bear that would take your picture and post it on Twitter.  It was an example of the type of project that kids could do to get them interested in computer technology.

My brain began to turn to mush with Marco Gralike’s talk on XML and 12c In-Memory Column store.  I’m sure I’m absorbed something but I’m not that familiar with Oracle’s XML features.  Still, at least I know that there are in memory features for XML which I can file away for the future.

Several amusing 10 minute Ted talks followed.  Most notable to me was Jonathan Lewis’ talk about how virtual columns and constraints on virtual columns could improve cardinality estimates and thus query performance.

Cary Millsap talked about a variety of things including things like what he covered in his book.  He shared how he and Jeff Holt were hacking into what I assume is the C standard library to diagnose database performance issues, which was pretty techy.

Gwen Shapira’s talk on Kafka was a departure from the Oracle database topics but it was interesting to hear about this sort of queuing or logging service.  Reminds me in some ways of GGS and Tibco that we use at work but I’m sure it has different features.

Alex Gorbachev gave a high level overview of Internet of Things architectures.  This boiled down to how to connect many possibly low power devices to something that can gather the information and use it in many ways.

Lastly, we went back to the Oracle database and my brain slowly ground to a halt listening to Chris Antognini’s talk on Adaptive Dynamic Sampling.  I had studied this for my OCP but it has slowly leaked out of my brain and by 4 pm I wasn’t 100% efficient.  But, I got a few ideas about things that I can adjust when tuning this feature.

Anyway, brief overview.  I’m back to normal OpenWorld tomorrow but it was all OakTable today.  It was a good experience and I appreciated the chance to speak as well as to listen.


Categories: DBA Blogs

Monday OpenWorld

Mon, 2015-10-26 22:10

It was a good first full day at Oracle OpenWorld.  It started with the keynote led by Oracle’s CEO.  Of course he was very upbeat about Oracle’s products.  But, I found his comments about the economy and the way it affects IT spending more interesting than Oracle’s cloud products.  My translation is that companies have a lot of older systems that they can’t easily retire or upgrade but they want to quickly add all this new functionality.  I see that in my company so it rings true.  I don’t really believe that the cloud is the long-term answer but it makes me wonder what the real answer is.  I always come back to prioritization.  I think prioritizing spending is more important than moving things to the cloud.  You can’t afford to do everything so you have to make tough choices about what to spend your IT dollars on. That’s my opinion at least.

Next I went to a session on Coherence.  I kind of went out of a sense of obligation since our company owns the product.  But, it was a surprisingly good session.  It had a lot in it about Java 8 and the new features in it for parallel processing.  It made me want to dust off my Java skills and generally think about parallel processing in the Oracle database and how it relates to that in Hadoop, Scala, etc.

I went to two sessions on analytics, again out of a sense that I needed to learn about analytics and not due to any enthusiasm about it.  The first session was really interesting, but the 3:30 session almost literally put me to sleep.  The first session reminded me of some of the things in Craig Shallahamer’s forecasting book such as making a model of a system and doing validation of the model.  Analytics seems to follow a similar process. But, by the late afternoon a non-technical session on analytics in banking nearly knocked me out.

Wedged between my two analytics sessions I went to a very cool In-Memory Option boot camp.  I have not had the time or taken the time to look at the In-Memory Option and I got a nice fast hour-long exposure to it.  I don’t know if the other people in the class were lost because there were a lot of explain plans flying by but it is the type of stuff I’m interested in so it was nice that it was so technical.  The In-Memory Option reminded me a lot of Exadata smart scans and hybrid columnar compression.

Strangely enough multiple speakers pronounced columnar differently than I have done so I guess I will have to change.  They emphasize the second syllable but I usually emphasize the first.

I also snuck in to the OakTable World presentation by Tanel Poder.  It had to do with querying Hadoop clusters from Oracle databases using odbc/jdbc.  Pretty cool.  I also got to scope out the venue for my talk tomorrow in the process.

That’s enough for today.  I got a lot of good information.  I’ve slotted tomorrow for OakTable world so it will be interesting to see what all I can learn there.





Categories: DBA Blogs

Reviewing Delphix blog posts before OpenWorld

Thu, 2015-10-22 10:13

I just finished reviewing my Delphix blog posts in preparation for the talks that I will give during OpenWorld. I find myself referring back to my blog to help me remember what I have done in the past. I was thinking that I needed to jog my memory so that I could answer questions when I give my talks.  Some of the Delphix topics that I am speaking about occurred a year or two ago so my memories are fuzzy.  But, reading my own posts brought a lot of the details back.

I thought I would list the Delphix posts, even though people can find these just by searching my web site. If you are coming to my talk and want more details or if you just want all the Delphix related information on my site I have collected it here.

I have two talks scheduled during OpenWorld next week.

The first talk is at OakTable World at 9 am on Tuesday.

The second talk is at Delphix Sync between 3 and 4 pm Thursday.  The second talk is a ten minute “lightning talk” version of the first.

I hope to see you at one of the talks and if not I hope this post is valuable to you.


Categories: DBA Blogs

Toastmaster Talk – DBA Toolkit

Mon, 2015-10-19 16:55

Here is a YouTube video of a short Toastmasters talk of mine about a DBA topic.  It was probably too technical for the audience but may interest the readers of this blog.

Here was a post about a similar topic:

  • Bobby
Categories: DBA Blogs

My Delphix presentation at OakTable World

Wed, 2015-10-07 17:52

It is official.  I will be doing my Delphix presentation at OakTable World during the Oracle OpenWorld conference at the end of this month.  My talk is at 9 am on Tuesday, October 27.

I will describe our journey as a new Delphix customer with its ups and downs. I tried to have the spirit of a user group talk where you get a real person’s experience that you might not get from a more sales oriented vendor presentation.

Kyle Hailey, a OakTable member and Delphix employee, will host my talk.  I have been very impressed by Kyle’s technical knowledge and he will be with me to answer questions about Delphix that I could not answer.  I think it will be a good combination of my real world user experience and his depth of technical background in Delphix and Oracle performance tuning.

If you are going to OpenWorld and if you want to know more about Delphix come check it out.  Also, feel free to email me or post comments here if you have any questions about what the talk will cover.


Categories: DBA Blogs