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Mar 16 2017
William Sescu

10th CH Exadata Community Meeting

By | Database Administration & Monitoring | One Comment

Yesterday (15th of March), the 10th Switzerland Exadata Community Meeting took place. It was not a meeting only about Exadata, but also about the Oracle Database Appliances which became more and more popular. It is interesting, how many companies in Switzerland already use Exadata’s or ODA’s. A big topic was the Exadata 12.2.1.1.0 software release which includes over 30 unique software features and enhancements, like better analytics, better transaction processing, better consolidation, more secure and…

 
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Feb 04 2017
Franck Pachot

Exadata Express Cloud Service: MAX_PDB_STORAGE

By | Cloud, Database Administration & Monitoring | No Comments

The separation of roles between system DBA and application DBA is the way to go for agile development and the PDBaaS managed service is an excellent way to play with this concept: You are PDB administrator but not the CDB administrator. Here is an example about tablespace creation/deletion, and the kind of problems that may arise with this architecture.  

 
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Feb 01 2017
Franck Pachot

Running SLOB on Exadata Express Cloud Service

By | Database Administration & Monitoring | One Comment

The Exadata Express Cloud Service is a managed PDBaaS: Oracle is the system admin and the CDB database administrator, you are the PDB administrator. You connect with a local user, PDB_ADMIN, which is no SYSDBA privilege but has a PDB_DBA which has nearly all DBA rights, but with some features disabled by lockdown profile. I have no worry about the performance on this service: it is an Exadata X5 half rack bare metal (my guess),…

 
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Jul 29 2016
Franck Pachot

Exadata X-5 Bare Metal vs. OVM performance

By | Database Administration & Monitoring | No Comments

The Exadata X5 can be installed Bare Metal or Virtualized. The latter one, Oracle VM allows to create multiple clusters on one machine, is more complex for installation and for storage capacity planning. But it allows a small flexibility on options licencing. Those are the real challenges behind the choice. However, when we talk about virtualization, most of questions are about the overhead. Last week, we did some tests on same machine with different configuration,…

 
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Mar 07 2016
Franck Pachot

GTT in Exadata are eligible to SmartScan

By | Database Administration & Monitoring | No Comments

I wanted to check if Exadata predicate offloading can occur on Global Temporary Tables. Actually, I thought it did not and I was wrong. I was ready to post that as an hypothesis for https://community.oracle.com/thread/3903836 but, before any post to forums, I try to test what I say because I may be wrong, or things may have changed from versions to versions. Here I will show how it’s easy to quickly test an hypothesis. And…

 
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Feb 09 2015
Franck Pachot

Never gather WORKLOAD stats on Exadata…

By | Database management | One Comment

For Exadata, oracle has introduced an ‘EXADATA’ mode which sets a high transfer rate (with IOTFRSPEED as in NOWORKLOAD statistics) and set a MBRC (as in WORKLOAD statistics). Those values are set rather than gathered because all the SmartScan optimization done at storage cell level, which makes the multiblock reads less expensive, is difficult to measure from the database. Here I will explain what I stated in a previous blog: direct-path reads are not counted…

 
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Sep 23 2014
Franck Pachot

How to measure Exadata SmartScan efficiency

By | Database management | No Comments

A thread on OTN Forum about Exadata came to the following question: “But how can I monitor if it is effectively used or not?”. This is a common question. There are 3 exclusive features coming with Exadata, and instance statistics can show their usage. Even better: two of them can even be checked on your current (non-Exadata) system. And that is good to foresee how Exadata can improve your workload. Let’s find how to measure the…

 
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May 28 2014
Franck Pachot

Oracle Exadata – poor optimization for FIRST_ROWS

By | Database Administration & Monitoring | 3 Comments

In a previous blog, I discussed the difference between rownum and row_number(), in particular their behaviour in implicitely adding a first_rows(n) to the optimizer. That reminded me that I forgot to blog about an issue I encountered and which concerns both approaches. It was on an Exadata: a nice full table scan with smartscan was taking a long time. And forcing to an index access – with a very bad index – was better. The…

 
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