It’s time for the next article with ODBV visualisation 🙂 This time let’s examine the difference between move and shrink – this is very common question on a lot of trainings. You can find a lot of great articles in the Internet regarding this subject but I think that visualisation really helps to understand what […]
From time to time I get questions on my trainings, what is the difference between TRUNCATE TABLE and TRUNCATE TABLE DROP STORAGE… well, there is no difference because DROP STORAGE is default 😉 DROP STORAGE Specify DROP STORAGE to deallocate all space from the deleted rows from the table except the space allocated by the […]
Recently I wanted to demonstrate to some people on my training, how Oracle database maintains blocks in a datafile – what happens after truncate, truncate with drop storage clause, delete, regular insert, direct path insert and so on… I didn’t find any tool for that so I’ve written my own. It’s core code is based […]
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 […]
Since the promotion tickets for the first international Oracle conference in Poland (poug.org/en) are sold out, I’ve decided to create a little contest allowing you to win a voucher code for -20% of the current ticket price. The task is easy, but you have to use DBA and DEV skills to resolve it. So the […]
Sometimes you drop something by accident – you know, the syndrome called "An Enter Too Far". If you drop a table, the case is easy – you can use recyclebin to restore it. But when you drop a package or procedure… well, you have a problem 🙂 Of course, you could use a flashback query […]
This will be just short article with very simple trick, showing how to match the ASMLib devices with actual multipath devices. I’m sure there is a simpler way… but I just love using AWK 🙂 If you know a simpler or more elegant solution – please post it in the comments section. My solution looks […]
Let’s fuckup the cluster! Of course after this operation, the final state of the processes can look like this: The cssd service will not be able to start, because there are no voting disks: OK, so let’s try to stop the cluster services: Now we will have to start CRS in exclusive mode and start […]
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 […]
Virtual hosts on Exadata with OVM are HVM and not PV. This is one of the limitations of Infiniband SR-IOV – can’t be used with PV. So there is a qemu used to emulate the hardware While accessing a physical device from within a DOMU we can see that actual work is being done on […]
This week I had a "pleasure" of reimaging Exadata server to use OVM. During this process we hit interesting problem – after the reimaging process there was no bridge at DOM0, corresponding to the client network – because of this, the OEDA sofware returned an error like this: The error was produced by this script: […]
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 😉
I was second time at the conference organized by UKOUG but this time I had a pleasure to be among the speakers 🙂 To reach the level set by other speakers was impossible – but trying it gives a lot of fun. Since I did a live demo and I didn’t have any slides – […]
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’ve wrote about privilege escalation with external tables in this post: https://blog.ora-600.pl/2014/12/23/simple-technics-of-privilege-escalation-part2-dbasysdba/ This time we will try to list all files within directory object, to which we have no EXECUTE privs. This is possible due to great new feature of database 12c that allows to use metacharacters to match multiple files in external table. I […]