Parse it 🙂 Simple, right? But for sure we are not going to use tkprof for 14 000 trace files, are we? We don’t have Diagnostic Pack and we just started a complete database tracing for an hour or two, because the customer said that they encounter performance problems during this period. Now you have […]
In my previous post I described a case of "enq: TX – row lock contention" that was actually a network latency problem. More and more those kinds of problems (it seems like history happens all over again) caused my friend (Radosław Kut) and me to write a simple tool to analyze SQL performance from a […]
So we had a doubtful pleasure of migrating a few databases from Oracle Exadata X3-2 to Oracle Exadata X7-2 Cloud at Customer. Why doubtful? Well, this a material for a whole different story with a lot of beer – let me just say, that CC gen 1 was a bit rough around the edges 😉 […]
At Trivadis Performance Days 2018 (awesome event by the way) I promised to deliver ODBV3 with support for ASM – and here it is! 🙂 https://github.com/ora600pl/odbv To use it, you have to have access to a user at ASM level with at least SYSDBA privilege. In the connect string you don’t have to add AS […]
It has been crazy few months – organizing POUG2018 took a lot of energy but it was satisfying as hell! 😀 This weekend I had some time to prepare a new version of ODBV for Trivadis Performance Days 2018 where I’ll be talking about the internals of database block storage. The series of articles about […]
If you work as a consultant, getting remote access to your customer is sometimes a nightmare! Even when you’ll get one, there a times when you just want to get your job done and finish this nightmare. For example, there are times when it is easier to dump a statspack repo and do offline analyzes. […]
(Please tell me that I’m not the only one who thinks "Index Organized Table" instead of "Internet Of Things" when hearing IOT…) This post is inspired by Connor McDonald and his blog post from a year ago about direct mode operations and IOTs. You can read it here: https://connor-mcdonald.com/2016/07/04/direct-mode-operations-on-iots/amp/ While writing a redo parser for […]
While researching redo log internals for V00D00 we had to face the fact, that we know shit about real transactional behavior. When I say "real", I mean – under the hood. Even with a very simple stuff like COMMIT and ROLLBACK we were constantly amazed by the internal mechanisms. Today let’s take ROLLBACK under the […]
Before you proceed, please check out this short article written by Tanel Poder: https://blog.tanelpoder.com/2010/09/02/which-number-takes-more-space-in-an-oracle-row/ In the documentation, you can find the following explanation about the internal numeric format: Oracle stores numeric data in variable-length format. Each value is stored in scientific notation, with 1 byte used to store the exponent and up to 20 bytes […]
Joining the OTN Appreciation Day 🙂 I really like the new pragma UDF feature for PL/SQL – it makes me believe that context switches will be less painful in the future 🙂 I wrote a little bit more about it here: https://blog.ora-600.pl/2015/10/29/oracle-12c-pragma-udf-the-truth/ And Martin Widlake wrote a lot about it here: https://mwidlake.wordpress.com/2015/11/11/pragma-udf-some-current-limitations/
I know – everyone knows, that PL/SQL packages are faster than stored procedures. If you’ll ask anyone at the training or in your dev team "what is better" – you’ll (almost) always hear: PL/SQL packages. But why exactly? The documentation says: The first time you invoke a package subprogram, Oracle Database loads the whole package […]
Years pass by and I think that the more I’m trying to understand the Oracle RDBMS – the less I know. Recently I started to examine the behavior of session cursor cache and I noticed an interesting thing. But let’s start from the beginning like we should 🙂 The documentation says: About the Session Cursor […]
Well it has been a month since my last blog post, so I think it’s time to write something 🙂 Those context switches can be a real pain in the ass – there is a great article by Frits Hoogland about context switching from SQL to PL/SQL – you can read it here: https://fritshoogland.wordpress.com/2016/01/23/plsql-context-switch/ You […]
I’ve created recently a script in AWK to create wait event histogram from 10046 trace file. The script can be found here. I thought that a good idea would be creating a little script to analyze the contents of 10053 and 10046 events together. So I wrote one 🙂 You can download it here: http://ora-600.pl/oinstall/format_10046_10053.awk […]
I wrote a very simple script in AWK to create wait event histogram (for db file scattered read, db file sequential read, direct path read and direct path read temp) based on 10046 trace file with wait events. Maybe someone will find it useful 🙂 The sample output looks like this: Enjoy 😉
Some time ago one of my students asked me if temp segments are being written to flash disks on Exadata… Well I wasn’t sure 🙂 But recently I had some time to check it. Let’s create some query that will generate temp segment: Great. Now we have to do some tracing at the cell servers […]
I had a pleasure to work with my colleagues from Oracle – Radosław Kut and Krzysztof Marciniak – at comparing the performance of In-Memory queries between Sparc M7, Intel® Xeon® X5670 and Intel® Xeon® E5-2699. You can find results of our findings in this presentation: https://www.oracle.com/webfolder/s/delivery_production/docs/FY16h1/doc17/DB12c-on-SPARC-M7.pdf Following their methodology I’d like to present appropriate results […]
Thanks to Oracle I had a possibility to test the new Sparc M7 with DAX coprocessors to boost In-Memory performance. You can read about it here and here My first thought was – how to check if and when the DAX coprocessors are being used? When you have a POC for Exadata, you want to […]