The Oracle Active Session History (ASH) – a real treasure trove

When Oracle introduced the Active Session History (ASH) a new gate of tuning and monitoring options was opened.  Yes we had statspack, extended tracing and so on but all these tools were mssing a time(line) dimension. For example statspack reports and later AWR reports are flattened aggregations of numbers carefully to interpret as details are flushed as you always have only a look on an aggregated view of performance metrics.

Yet another workaround for missing AVG() function for the Oracle interval type

Isn't it similar to you experience with Oracle SQL? there are a few places in the Oracle SQL implementation where you think why didn't they think it through to the end or did they only partially implement a feature?

So you are not the only one suffering from this. It does not mean Oracle SQL is inconsistent as it is indeed a mighty mature tool to handle date and structures in the Oracle database.

Coming (more...)

dramatic differences of in memory scanning performance on range queries

Given following two identical tables, on which run the same SQL,  replicated in memory with oracle in-memory option - one table created out of the other.
each tables covers 24m rows.
Same structure ...

Why the In-Memory Column Store is not used (II)

Now after some research - I detected one simple rule for provoking In-Memory scans :

Why the In-Memory Column Store is not used (I)


Now finally after a long period of waiting - and looking presentations and reading blogs I was able to do In-Memory databasing on my own. Having sampled some theoretical background how a a pure In-Memory Db works with SAP HANA; my expectations on the Oracle In-Memory Option were high. Also because Oracle promised it would work without code change, out of the box.

The setup

The Oracle database is located on Sun Solaris Machine (more...)

Oracle 12C – In-Memory Option Resources

Hi folks,

Introduced as an Option Oracles In-Memory option will change the world of databasing also like SAP HANA does; Since July the release is out but the search for resources and documentation is  poor;

Here some useful links I found.

Non-Oracle Resources


Oracle Documentation

Concepts (found a small passage) ...



just started the list - wiil enhance it - from time to (more...)

The empire strikes back!

About 3 years ago SAP started to create a new database engine, SAP HANA, with a pure In-Memory concept. SAP aggressively move it's new database to it's software stack. The database was not used as cache but for running Enterprise Application satisfying both OLTP and OLAP demands on the same database.  

As oracle announced the new Oracle 12c in late 2012 there the 'c' was for cloud based computing, means the simplification of creating (more...)

Conditional Unique Indexes

Matrix : What you must learn is that these rules are no different than rules of a computer system. Some of them can be bent, others can be broken. Understand?
Usually an unique index grants the uniqueness of all rows in a specific table which have non-null values; But (more...)

InfoQ : Running the Largest Hadoop DFS Cluster

Since I joined a Big Data Event : Frankfurter Datenbanktage 2013 - I started to take also a look to non-relational technics too. The RDBMS is not for every asepct the correct and fitting and fulfilling answer to all data related IT challenges. 

Frequently I wondered about how facebook (more...)

Learn from the smaller one’s : Native support for ENUM Types

Gerhard a colleague is dealing with postgres databases and was very suprised how many features are very oracle like. For example the same concept of Sequences as in Oracle. But then he detected the postgres enum native type support in postgres and asked me if the same feature would exist in Oracle.