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Oracle 11g

LOB : « enq : HW contention » 

Aprés le post sur « Utilisons les securefile », revenons sur le sujet LOB avec une approche performance, stockage.

 Nous rencontrons parfois des modèles de données étranges, nous aurions envies en tant que DBA de tout reprendre à zéro pour refaire un modele relationnel en 3em forme normal (3NF), plus efficace et mieux conçu dans notre « RDBMS » favori, mais la réalité étant

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Oracle space management & recycle bin

This post describes some basic Oracle database management issues database administrators might be confronted with. It is about space management and differences observed while monitoring the available space from several point of views (tablespace/datafile) in Grid Control 11g. It also relates and explains an issue (ORA-01652) observed on pre 11.2 Oracle releases (targets) concerning the tablespace/datafile space management and the… 

Diving into Databases

By dbi services, we are a few poeples passionate by diving.
We take this opportunity to let you dive into the two databases lakes Oracle and SQL server and see their similarities and differences. For this first level of diving (named ODD), we will not going too deep and not have narcosis or

databases toxicity.
As always, we’ll start with

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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 the tables AUD$ and/or FGA_LOG$.

Inside Grid Control

Lors de mon activité de consultant, et suite à un bug qui n’affiche pas correctement le nombre de CPU (OMS 10.2.0.5, agent 10.2.0.5 et linux x86_64), je me suis intéressé à la manière dont Oracle Enterprise Manager Grid Control (OEM GC) récupérait les informations de mémoire et de cpu sur les différents hôtes surveillés par ce dernier.

RMAN backup is failing due to “corrupt blocks”

Last week, I was not able to complete a backup because of the ORA-19566 error: “exceeded limit of 0 corrupt blocks”. Here is what you can do to fix it. Starting Point: backup error Here is the starting point of this case. The following error is found in the RMAN Backup log file: allocated channel: ch1 channel ch1: sid=25 devtype=DISK… 

Oracle Basics (3) – Database startup and shutdown

It’s already quite a while that I posted my last article on the Oracle basis, so I decided to take some times in the train to continue this small serie.
This time, I’m going to speak about one of the root of Oracle administration, starting and shutting down a database.

Startup and shutdown processes within oracle databases are splitted in

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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. 1. Statistics restore This method uses the procedure dbms_stats.restore_%_stats, where % can be table, schema, database, and fixed_objects. This is… 

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.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

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