Whilst perusing the Oracle database documentation, I noticed something which caught my eye: As well as reading the documentation online as HTML or downloading as PDF for viewing on your computer etc, you can also download it in formats (Mobi and ePub) designed for eReaders such as the Kindle and iPad (the latter obviously isn’t “just” an eReader). For information on format support, there’s a handy table on Wikipedia. It looks like the availability of mobi/epub files isn’t universal.

Oracle XE 11gR2 beta has just been released, some details here and download here. It’s not a great deal of use for sandboxing DWH-specific stuff, given this list of excluded functionality (and this is by no means everything that’s not included): Bitmapped index, bitmapped join index, and bitmap plan conversions Oracle Partitioning Parallel Data Pump Export/Import Parallel query/DML Parallel Statement Queuing (source) However, it’s always interesting to have to hand for trying out other things.

This post expands on one I made last year here about sampling frequency (of I/O throughput, but it’s a generic concept). The background to this is my analysis of the performance and capacity of our data warehouse on Oracle 11g. Before I get too boring, here’s the fun bit: Pork Pies per Hour (PP/h) Jim wants to enter a championship pork-pie eating competition. He’s timed himself practising and over the course of an hour he eats four pork pies.

I wrote last year about Graphing I/O data using gnuplot and Oracle V$SYSSTAT, using a script from Kevin Closson in his article How To Produce Raw, Spreadsheet-Ready Physical I/O Data With PL/SQL. Good For Exadata, Good For Traditional Storage. Here I’ve got a simple comparison of the data recorded through this script (in essence, Oracle’s V$SYSSTAT), and directly on the OS through HP’s MeasureWare. It’s graphed out with my new favourite tool, rrdtool:

Over the last few months I’ve been doing a lot of exploring of OBIEE Systems Management data, covered in a mini-series of blog posts, Collecting OBIEE systems management data. There are a vast number of counters exposed, ranging from the very interesting (Active Sessions, Cache Hits, etc) to the less so (Total Query Piggybacks, although for some seriously hardcore performance tuning even this may be of interest). This short blog post is about a couple of counters which I’ve been monitoring but which looks to not be entirely reliable.

I’ve added two new toys to my geek arsenal today. First is one with which I’ve dabbled before, but struggled to master. The second is a revelation to me and which I discovered courtesy of twitter. rrdtool rrdtool is a data collection and graphing tool which I’ve been aware of for a while. I wanted to use it when I wrote about Collecting OBIEE systems management data with JMX, but couldn’t get it to work.

A chap called Kevin posted a comment on a previous posting of mine asking did you ever come across anything that could be used to change the LDAP server settings from a command line (admintool.exe, UDML, or otherwise)? I did a quick play around with some UDML and it appears that you can. Set up the initial LDAP server definition in the RPD First I added a dummy LDAP server to samplesales.

Cary Millsap recently published a paper “Mastering Performance with Extended SQL Trace” describing how to use Oracle trace to assist with troubleshooting the performance of database queries. As with all of Cary Millsap’s papers it is superbly written, presenting very detailed information in a clear and understandable way. (and yes I do have a DBA crush ;-)) It discusses how you can automate the tracing of specific sessions on the database, and requiring the application to be appropriately instrumented.

I’ve been doing some work recently that involved the use of Materialised Views on Oracle 11g (11.1.0.7), particularly around PCT refresh. There are some things that are not clear from the documentation, or are actually bugs so far as I’m concerned, and I’ve detailed these below. In this example I was working on part of a DWH with c.2 millions rows aggregated up daily. One of the things that I spent a long time trying to get to work was Partition Truncation when using PCT refresh.

Poking around on My Oracle Support today, I found a link to a white paper dated November 2010, titled “Best Practices for a Data Warehouse on Oracle Database 11g”. It’s new to me and I’ve not noticed a blog post announcing it, so I thought I’d share it here. It’s by Maria Colgan, who has posted in the past on both the Inside the Oracle Optimizer blog and The Data Warehouse Insider blog.