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April 2017

Indexing in Oracle, Fragmentation

I just uploaded my slides from Collaborate 2017 to Slideshare, but also, the findings missing from my slide deck I used for Oak Table World on War of the Indices- Oracle and SQL Server.  Feel free to download them here.

Oracle and SQL Server Index Comparison

This post has a lot of the support code and data for my Oak Table Talk that I’ll be giving at IOUG Collaborate 2017 in Las Vegas on April 5th, 2017.  

A quick look at Oracle 12.2 performance instrumentation

Thanks to the prep-work done by Andy Colvin, who continuously and boldly goes where no man has gone before, one of our Exadata systems in the lab is now fully upgraded to It comes fully equipped with the matching cellos to support all the cool new features. Exciting times!

The reason for this post is simple: I have started working on our talk for @Enkitec’s E4 conference in June but thought I’d share this little article with you as a teaser :) There might be one or two more of these posts but if you want the full story make sure you catch us (online) during the conference.

Oracle Security Training Manuals For Sale

I had a reason today to go to our company storage for something today and whilst moving other things around to find what I needed I discovered two A4 boxes with printed manuals for some of our recent training classes....[Read More]

Posted by Pete On 05/04/17 At 02:22 PM

12.2 Some Cool Partitioning New Features (Big Wheels)

I previously discussed just how easy it is to convert online a non-partitioned table to be partitioned with Oracle Database 12.2. Thought I might run through a number of really cool new partitioning features and capabilities that were also introduced in 12.2. To start, I’m just going to create a basic range-partitioning table and populate […]

A performance deep dive into column encryption

Actually, this is a follow up post from my performance deep dive into tablespace encryption. After having investigated how tablespace encryption works, this blogpost is looking at the other encryption option, column encryption. A conclusion that can be shared upfront is that despite they basically perform the same function, the implementation and performance consequences are quite different.

How to Perform a Security Audit of an Oracle Database Training in Athens, Greece

I will be teaching my two days class How to Perform a Security Audit of an Oracle Database in Athens, Greece on May 16th and 17th 2017 organised by Oracle University. This is a great class that helps you understand....[Read More]

Posted by Pete On 04/04/17 At 02:45 PM

12cR2 DBCA, Automatic Memory Management, and -databaseType

This post explains the following error encountered when creating a 12.2 database with DBCA:
[DBT-11211] The Automatic Memory Management option is not allowed when the total physical memory is greater than 4GB.
or when creating the database directly with the installer:
[INS-35178]The Automatic Memory Management option is not allowed when the total physical memory is greater than 4GB.
If you used Automatic Memory Management (AMM) you will have to think differently and size the SGA and PGA separately.

Block Names

There are a number of tiny details that I can never remember when I’m sketching out models to test ideas, and one of those is the PL/SQL block name. Virtually every piece of PL/SQL I write ends up with variables which have one of two prefixes in their names “M_” or “G_” (for memory or global, respectively) but I probably ought to be formal than that, so here’s an example of labelling blocks – specifically, labelling anonymous blocks from SQL*Plus using a trivial and silly bit of code:

When automatic reoptimization plan is less efficient

11gR2 started to have the optimizer react at execution time when a misestimate is encountered. Then the next executions are re-optimized with more accurate estimation, derived from the execution statistics. This was called cardinality feedback. Unfortunately, in rare cases we had a fast execution plan with bad estimations, and better estimations lead to worse execution plan. This is rare, but even when 9999 queries are faster, the one that takes too long will gives a bad perception of this optimizer feature.