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HOWTO: Viewing XML data in V_$CELL_% storage cell SYS views

Got a small question from Frits if I could help him make some XML data readable in one of the SYS.V_$CELL_% / V$CELL_% views. I have been a bit busy, in between jobs, to try to make some of those XML columns more readable anyway (for myself and others) so…lets have a go at it. …

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Storage Indexes vs Database Indexes Part II: Clustering Factor (Fast Track)

Two posts in two days !! Well, with Christmas just around the corner, I thought I better finish off a couple of blog posts before I get fully immersed in the festive season The Clustering Factor (CF) is the most important index related statistic, with the efficiency of an index performing multi-row range scans very much […]

Storage Indexes vs Database Indexes Part I MIN/MAX (Maxwell’s Silver Hammer)

It’s often stated that in Exadata, you don’t need conventional database indexes anymore as everything runs so damn fast that indexes are simply a waste of time and space. Simply drop all database indexes and things will run just as fast. Well, not quite … There are many many scenarios where database indexes are still […]

Exadata Storage Indexes Part V: Warming Up (Here Come The Warm Jets)

As I mentioned in a previous post, there are a number of Similarities between Storage Indexes and Database Indexes. One of these similarities is the “warming up” process that needs to take place before indexes become “optimal” after either the Storage Server (in the case of Storage Indexes) or the Database Server (in the case […]

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 […]