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Enkitec at UKOUG 2012


Here’s the list of Enkitec’s UKOUG conference sessions – I will be delivering 3 sessions, including a 2 hour Exadata hacking session!

We are also sponsoring the ping-pong table (woo-hoo! :) and will give away 3 super-cool Sphero balls … that should be fun! ;-)

See you soon!


Exadata Storage Indexes Part IV – Fast Full Table Scans (Speed of Life)

OK, let’s look at Storage Indexes in action. But first, following is the setup for the various demos to come. I basically create one table called BIG_BOWIE that’s about 1GB in size and then simply create another table called DWH_BOWIE where the contents of this are re-insert into itself a few times to get to about […]

Exadata upgrade to version and ASR

Recently we upgraded an Exadata to the currently latest version, The Exadata software itself consists of an image for the storage servers (the storage servers are essentially re-imaged), and a set of updates for the database/computing nodes, including: firmware for ILOM (lights out adapter), BIOS, LSI RAID adapter, Infiniband adapter, linux kernel, drivers, mandatory packages, to name some.

Select statement generating redo – and lost write detection

Gwen Shapira has written a nice summary of a problem case where the classic wait interface based troubleshooting method is not always enough for troubleshooting low-level issues.

The top SQL + top wait approach should usually be used as the starting point of troubleshooting a session, workload etc, but often the troubleshooting does not stop there. So, when the wait interface and related tools don’t explain the problem well enough, then you either start guessing from there or dig deeper into performance data. And Gwen used the V$SESSTAT metrics (using my Snapper tool) to understand why was a select statement generating redo this time (there are multiple reasons for that – and V$SESSTAT tells you why).

Oracle exadata: pam and temporary user-lockout.

If you are administering an Oracle Exadata database machine, which base operating system image (the operating system version with which it system came) is Linux and version (current version is viewable with the command ‘imageinfo’, which needs root account privileges) or higher, and multiple users are accessing the system with password authentication, this blogpost might be an interesting read. Also, if you have witnessed temporary lockout of the oracle user, or other users: this blogpost describes the reason and a potential resolution.

Exadata Storage Indexes Part III – Similarities With Database Indexes (Same Old Scene)

As discussed previously, there are quite a number of differences between Storage Indexes (SIs) and Database Indexes (DIs). However, there are also a number similarities between both of them as well. The obvious one is that they’re both designed specifically to reduce the overheads associated with retrieving the required data out of the database. Both index structures provides […]

ORA-00600: internal error code, arguments: [kmgs_component_init_3], [60], [65], [17], [], [], [], [], [], [], [], []

Recently I patched an grid infrastructure to an higher version. After the patching I started the grid infrastructure on that host, and ASM was unable to start. Looking in the alert.log file of the ASM instance it turned out that upon starting ASM, even before the contents of the pfile/spfile was displayed, the ASM crashed with the ORA-00600 error:

Exadata Storage Indexes Part II – Differences With Database Indexes (Space Dementia)

Let’s explore some of the key differences between Storage Indexes (SI) and Database Indexes (DI). In no particular order, they include: SIs are structures that exist only within the storage servers of an Exadata box, while DIs logically exist and can be accessed within the database servers. SIs are purely memory only structures while DIs are […]


There’s never enough time to read everything that’s worth reading, so even though Guy Harrison’s blog is one of the ones worth reading I find that it’s often months since I last read it. Visiting it late last night, I found an interesting batch of articles spread over the last year about the performance of SSD – the conclusions may not be what you expect, but make sure you read all the articles or you might end up with a completely misleading impression:

Exadata Storage Indexes – Part I (Beginning To See The Light)

Thought I might discuss Exadata Storage Indexes, explore what they are, how they work and discuss their advantages and disadvantages. Following is but a brief introduction on this very cool Exadata feature. A Storage Index basically maintains summary information about database table data down on the Exadata storage servers. The information consists of the minimum value, the maximum […]