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Oracle

Oracle Database as our consultants live it every day: installation and patching, upgrades, RMAN backup and recovery, Data Guard, RAC, performance tuning, multitenant, licensing, and engineered systems such as ODA and Exadata.

set “_rowsets_enabled”=false

By Franck Pachot . This 12c ‘wrong results’ issue is thoroughly described by Mike Dietrich (https://blogs.oracle.com/UPGRADE/entry/switch_off_rowsets_enabled_in) and I’ve nothing to add. This blog post is there to be used as a reference for the comment in the following recommendation that we give to our 12c customers: alter system set “_rowsets_enabled”=false comment=’see http://dbi-services.com/blog/_rowsets_enabled’ scope=both; Our best practice is to document any… 

AWR when ASH CPU >> DB CPU

By Franck Pachot . I’ll present How to read an AWR report next month at UKOUG TECH15 and the first recommendation after checking Average Active Sessions is to verify that we are not in a CPU starvation situation. Here is a little demo to show how it looks like in an AWR report. In other words, I’ll demo the second… 

RMAN channels in RAC

By Franck Pachot . When you want to minimize the backup or restore duration, you can parallelize RMAN operations by allocating multiple channels. If you are in cluster, you can open channels from several nodes. Let’s see why, how, and a strange issue: need to set cell_offload_processing=false even if not on Exadata. Reason Why do I want to run backup… 

IBM Bluemix Database Cloud Service – My first trial

By Franck Pachot . Remember my first try of Oracle cloud when Larry Ellison announced the Cloud in june? This week at OOW15 Larry Ellison announced that IBM is not a competitor anymore for them, then I checked IBM Cloud: IBM Bluemix offers IaaS, PaaS and SaaS. As I did in my first trial for Oracle, I’m testing the simplest… 

DBA, turkeys and NoSQL hype

By Franck Pachot . We (DBAs) look at this NoSQL hype with a large smile. We know how powerful are SQL databases and we can’t imagine processing data seriously without it. And the technologies that come with NoSQL brings back the problem that we have solved with SQL databases. But can’t we ignore what is currently going on. Behind the… 

SQL> alter database switchover to …

By Franck Pachot . In 12c the manual switchover to physical standby requires only one command (ALTER DATABASE SWITCHOVER) instead of two (ALTER DATABASE COMMIT TO SWITCHOVER on each database). We usually recommend to use the broker and I wanted to see if the broker uses that new command or not. Let’s compare the alert.log for both manual and broker… 

Oracle Cloud Service – my first outage

By Franck Pachot . We experienced the first planned outage this week-end, so let’s see how it is notified and what happens. EMEA Commercial 2 – Amsterdam Outage notification before: subject: Announcement: Upcoming Mandatory Maintenance for Oracle Cloud e-mail date: 16 Octobre 2015 1:49 message: Start Time / End Time: Saturday, October 17, 2015 9:00:00 PM CEST – Sunday, October… 

You are in Standard Edition, when to worry?

By Franck Pachot . A previous blog post explaining what happens for those in ‘Standard Edition One’ had a “don’t worry” in the title because you can upgrade to SE2 with minimal additional cost – except when you have to buy new NUPs – and get only small additional limitation. I didn’t made such a post for people in Standard… 

11.2.0.4 support? Don’t worry until 2017

By Franck Pachot . Customers reluctant to go to 12c before 12.2, in addition to Standard Edition contract changes when going to 12c, has lead to lot of upgrades to 11.2.0.4 but what about support? Don’t worry. It’s supported for no additional cost until May 2017 Support levels Do you know why you pay support (per year about 20% of… 

Mapping In-memory CU to values: IMCU pruning

By Franck Pachot . In the previous post we have seen how In-Memory Compression Unit map to the physical persistent storage – table extents. Let’s see now how they are mapped to column values, allowing to optimize the scan in a similar way as Exadata Storage Indexes. The examples below will illustrate IMCU pruning and IMCU skip filtering. Here are… 

Mapping In-memory Column Store to datafile Row Store extents

By Franck Pachot . Oracle In-Memory is an hybrid solution: an In-Memory Column Store in addition to the traditional Row Store. In the IMCS, data is stored in IMCU (In-memory compression units) and metadata is in SMU (Snapshot Metadata Units) In the row store, data is stored in datafile extents and metadata is stored in the dictionary (and in datafile…