14. 12. 2018.

How to quickly check disk(s) speed limit on Linux – part 2

In the previous part of disk speed series you can see one way to test disk speed by using special options of the dd command. In this article another utility – hdparm will be described. What is common with the previous way of testing HDD disk performance is in it’s simplicity, meaning you only need […]

07. 12. 2018.

Oracle Forms 12c client deployment configuration options

Many Oracle users are still considering Oracle Forms/Reports as the best UI technology Oracle has to offer. It’s not surprising as Forms/Reports technology is very robust, developed through the decades, has proved in many large projects as very reliable and fast technology that leverage three-tier architecture (unlike Oracle APEX, very popular these days for building […]

04. 12. 2018.

How to quickly check disk(s) speed limit on Linux

Many times I can testify that IT professionals are talking about performance without even try the most simplistic tests to find out what are the HW capabilities/limits they have. One of the first things I usually do when facing with unknown environment is to run several tests to find out how much I can get […]

19. 11. 2018.

LOB data type side effect on DML trigger based auditing

I’ve been listening scary stories about all kind of issues related to LOB data types (there are many data types based on the LOB concept like Spatial, CLOB, BLOB, XML…). In this article I’ll put some light on one of the lesser known consequences related to mechanism how LOB works under the hood. To solve […]

18. 10. 2018.

Undo impact on Oracle Db performance

Many times I’ve been hearing how REDO is the most important to tune in order to have database running fast, but very rare I can hear that someone is mention UNDO as another piece of puzzle that is also extremely important to keep in good shape. In this article I’ll try to avoid what you […]

27. 09. 2018.

Non prefixed local index and slow SQL

Recently I’ve been asked to help explain why one query is running so slow based on only SQL text and table definition that is provided. As query was pretty big (several hundreds lines of code), at the first I thought that is mission impossible, as I have no explain plan available, no running stats, no […]

13. 09. 2018.

Bash performance tuning by example – How to delete 1 million files from file system, and how to do that fast?

In this article I’ll show my approach to solve real world performance problem by using bash scripting language.   Problem statement is: How to delete 1 million files from file system, and how to do that fast?   File system maintenance is important aspect of sysadmin job. It’s not only important to maintain file system, […]

06. 09. 2018.

Performance tuning by using optimistic instead of pessimistic locking – Part 2

In the previous blog I described how to implement optimistic locking logic by using ORA_HASH function call. Here I’ll explore another option that I frequently use – last time when the row has been changed. Let’s create test table by using DEPT table as a base with one additional column – MOD_TIME. For MOD_TIME column […]

24. 08. 2018.

Performance tuning by using optimistic instead of pessimistic locking

Even though Oracle Db started with optimistic locking many years back, old fashion programming style can still be observed too often. In this article I’ll explain why you should avoid using pessimistic locking as mach as possible, and will show one of the alternative way to do the same task by using optimistic locking. I’ll […]

16. 08. 2018.

Exadata / Linux crash – capturing kernel dump on Linux systems

This article has been motivated from real life issue experienced on Exadata system running a few dozen of Oracle databases. I have already written about Exadata shortcoming in one of previous articles where I stressed that one of the main disadvantages of Exadata machine is non-existent virtualization technology. Oracle recognizes Oracle VM as the only […]