Application integration & Middleware

Partition exchange preview in MySQL 5.6

MySQL 5.6 proposes improved partition maintenance through "partition exchange". Even if not yet available, dbi services performed some tests on the MySQL Community Edition5.6.2 m5 release (still under Development).

SQL Server Tuning: Detect SPARSE columns candidate

dbi services search and test all tools or functions possible to optimize or to win something to propose the best tuning possible in their client.The property of Spare columns is not the most used in client environment that we(…)

Compression advisor: excessive redo log file generation

Last week by a customer, we experienced an excessive redo log generation filling up rapidly the FRA (Flash/Fast Recovery Area) with archivelog files which caused the database to crash.

Oracle 11g R2: catupgrd.sql running for hours

During the last weeks, I was confronted to an uncommon bug during the database upgrade from security sensibledatabases. The upgrade was sticking for hours on the script c1101000.sql.  which tried to fill the column DBID with the database DBID of(…)

How to retrieve previous table statistics using Oracle dbms_stats

Sometimes, you need to modify the statistics of a table. There are various reasons: either for the performance analysis or because the execution plan changed. Oracle offers two methods: statistics restore or statistics export. Both are in the dbms_stats package.

A SQL statement is slow and suddenly fast? Have a look at “Cardinality Feedback”!

Discussing with some tuning gourous we were made aware about this feature. It is not so far from the adaptive cursor sharing perfectly described in  Chris's blog : http://antognini.ch/papers/BindVariablePeeking_20090718.pdfThis feature, compares the real execution(…)

Simulating and testing I/O performances with ORION

Since Oracle 11.2, Oracle provides ORION in the RDBMS binaries (in ${ORACLE_HOME}/bin). ORION is an I/O calibration tool allowing to simulating and testing I/O performances an Oracle database would be confronted with.   ORION basically supports four kinds of database(…)

Simulating database-like I/O activity with Flexible I/O

You do not want to install or configure swingbench, load runner etc. – just to test the performance of your I/O system based on filesystems? Then Flexible I/O is the right tool for you. This post provides an overview. In(…)

Oracle 11g Instance Caging – limit database CPU consumption

As you certainly already have heard Oracle 11g came with a new feature called “Instance caging”. This feature allows Oracle DBA to easily manage Oracle Instance CPU-consumption. How does it work? Quite easily … see below(…)

Oracle index compression: eliminating duplicate column values

Index compression comes from Oracle 8i and has quite the same mechanism as table compression. Index compression eliminates duplicate column values in the leaf blocks. Let's see how it works:(…)