17. 05. 2017.

To patch or not to patch, that is the question

I’ve modify words spoken by Prince Hamlet (William Shakespeare) a bit to explain one of the most common asked questions regarding the patching strategy especially in today’s complex IT environment. Probably very larger company have their specific policy how often they need to patch their IT infrastructure (for example storage/network/OS/databases/App Servers…). Parts of IT infrastructure […]

08. 05. 2017.

ReIM Consolidated documents cost resolution – performance improvement

After external contractor of the company where I’m working and Oracle Support were not able to find solution that would improve performance of the ReIM consolidated documents functionality, it’s time for me to take that challenge. Very quickly I’ve found the problematic SQL. Here I’ll provide only the important part, as the query is over […]

02. 05. 2017.

Example of how 10x technically faster code is 1000x slower in production

Recently I’ve solved this interesting issue on Oracle Retail production (code is from RPM – Retail Price Management). After upgrading Oracle Retail I found problematic part of code that is running fine in the old version of the RPM. In new version, developer has correctly changed the following part of code with much faster version […]

24. 04. 2017.

RAC One Node and automatic database relocation

I know there are other places where you can find why you don’t want that Oracle cluster automatically relocate RAC One Node from one node to the other (only one node can be active in RAC One Node configuration). First I’d like to explain what reasons can be behind that. Those are the most common […]

10. 04. 2017.

High Performance Computing in Retail Industry

I’d like to invite you at HIPEAC (European Network on High Performance and Embedded Architecture and Compilation) conference in Zagreb, April 27-28, 2017. There I’ll have a presentation about how to build IT system and how HPC technologies like parallelism and clustering can help. This is excerpt from the announcement. Josip Pojatina, Solution Architect, mStart, […]

29. 03. 2017.

AIX ADAPTER HARDWARE OR CABLE error

Here I’ll describe what will happen if your sysadmin are going to restart VIO servers and not co-ordinate activities with DBA. Although you have multipath configured, VIO servers are critical for normal IBM AIX LPAR functionality, as they share HW devices to LPAR VMs. If you are having RAC or RAC One Node configuration, this […]

28. 03. 2017.

Exadata part V – table & column compression

Exadata has columnar compression which is a very different from the regular table compression available on non Exadata Oracle databases. While normal compression algorithms (basic, OLTP etc.) are all block based, columnar compression is Exadata specific and is based on column instead of blocks. Here I want to show compression efficiency and time needed to […]

28. 03. 2017.

Exadata part IV – Exadata in Action

Here I’d like to show performance benefits of Exadata on complex, realistic SQL. Previous queries are more or less for toy, where the only purpose is to clearly show some feature/concept and what performance benefits you expect from it. The query I use in this article is known to be problematic on one of production […]

28. 03. 2017.

Exadata part III – reading from large partitioned table

This article is third in series about my experiences with Exadata database machine. Results in previous two articles are really great for Exadata. Here I’ll prove that there could be cases where Exadata is actually slower than Oracle database running on commodity hardware. Test case is serial reading from large partitioned (and sub partitioned) table […]

28. 03. 2017.

Exadata part II – parallel read

In this article I’ll cover parallel read from tables created in the first part that you can find here. As Exadata has many cores in all configurations, this is where I expect it has to shine. Let’s check it. 1. select /*+ parallel */ count(*) from tdh_nopartitions_normal; 12,27 sec 2. select /*+ parallel */ count(*) […]