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).
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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 have seen.
This article present a script to find the potential columns that can have the sparse property with the usage restrictions to make a space tuning in your database and especially for Data Warehouse (DWH).
The database example that we used, is AdventureWorksDW2008R2.
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.
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 the tables AUD$ and/or FGA_LOG$.
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. 1. Statistics restore This method uses the procedure dbms_stats.restore_%_stats, where % can be table, schema, database, and fixed_objects. This is an example for a restoration of a table with definite timestamp. The starting situation is:…
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.pdf
This feature, compares the real execution (number of returned/actual rows “A-rows”) with some expectations (number of expected rows “E-rows”) and chooses another plan for the next executions if the difference between the expectation and the actual result is too big. “Cardinality Feedback” is not well documented in the Oracle documentation.
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 activities based on either small or large I/O. ORION can, as any respectable I/O simulation tool, generate an adapted workload using a given percentage of reads and write operations.
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 order to simulate Oracle database I/O workload on filesystems, ORION cannot be used since it only uses raw or block devices (scratching the filesystem). To simulate Oracle database I/O behaviour on filesystems, we can use…
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
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: