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Jérôme Dubar

Restoring a database without having any controlfile backup

By | Database Administration & Monitoring, Database management, Oracle | No Comments

It should never happen but sometimes it happens. You just lost your datafiles as well as your fast recovery area (probably because most of the time these areas are on the same disks despite the recommendations). Normal restore operations with RMAN are quite easy and secure as far as you have backupsets for database, archivelogs, and spfile/controlfile: Step 1 – restore the spfile and start the instance Step 2 – restore the controlfile and mount…

 
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Jérôme Dubar

Easily manage dual backup destination with RMAN

By | Database Administration & Monitoring, Database management, Oracle | No Comments

Backup on disk with RMAN is great. It’s fast, you can set as many channels as your platform can handle for faster backups. And you can restore as fast as you can read and write files on disk with these multiple channels. As far as you’re using Enterprise Edition because Standard Edition is stuck to a single channel. Disk space is very often limited and you’ll probably have to find another solution to keep backups…

 
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Oracle Team

MERGE JOIN CARTESIAN: a join method or a join type?

By | Oracle | No Comments

By Franck Pachot . I’ll present about join methods at POUG and DOAG. I’ll show how the different join methods work in order to better understand them. The idea is to show Nested Loops, Hash Join, Sort Merge Join, Merge Join Cartesian on the same query. I’ll run a simple join between DEPT and EMP with the USE_NL, USE_HASH, USE_MERGE and USE_MERGE_CARTESIAN hints. I’ll show the execution plan, with SQL Monitoring in text mode. And…

 
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Morgan Patou

Documentum – DA 7.3 showing java.lang.NullPointerException on every actions

By | Application integration & Middleware, Entreprise content management | No Comments

Last year, we started to upgrade some Documentum Administrator from 7.2 to 7.3 and directly after, we started to see some NullPointerException on the log files. We are using DA 7.3 on some recent WebLogic Servers versions (12.1.3, 12.2.1.2). We usually deploy DA as a WAR file (so not exploded) with just the dfc.properties, keystores and logs outside of it. This is the kind of errors we started to see as soon as it was…

 
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Morgan Patou

WebLogic – Cannot register for disconnect events on local server

By | Application integration & Middleware | No Comments

When working with WebLogic, there will probably be a moment when you will ask yourself: damn, what is wrong? Nowadays, software are so complex that it is kind of easy to introduce bugs/non-wanted behaviors in them… In this blog, I will present a small thing that just blew my mind when I faced it: I had a fully working WLS on which I executed a WLST script in order to configure the SSL Ciphers for…

 
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Clemens Bleile

Trace files segmented in multiple parts as a workaround for bug 23300142

By | Database Administration & Monitoring | No Comments

Today I visited a customer, who deleted a Data Guard configuration (i.e. a temporary Data Guard setup through the broker was deleted). The LOG_ARCHIVE_DEST_STATE_2 on the primary database was set to DEFER temporarily. That resulted in trace-files with name *tt*.trc to become huge (GBytes after a couple of days). Analysis showed that this was caused by bug 23300142 in 12.1.0.2. See My Oracle Support Note Bug 23300142 – TT background process trace file message: async…

 
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Oracle Team

CDB resource plan: shares and utilization_limit

By | Database Administration & Monitoring | 2 Comments

By Franck Pachot . I’m preparing some slides about PDB security (lockdown) and isolation (resource) for DOAG and as usual I’ve more info to share than what can fit in 45 minutes. In order to avoid the frustration of removing slides, I usually share them in blog posts. Here is the basic concepts of CDB resource plans in multitenant: shares and resource limit.  

 
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Oracle Team

Instance Caging and multitenant: do the right setting

By | Database Administration & Monitoring | No Comments

When you want to do instance caging, you have to set manually CPU_COUNT and to set a resource manager plan. If you By Franck Pachot . only the CPU_COUNT no instance caging will occur. Except during the maintenance window where the maintenance plan is set internally. You don’t want that kind of unpredictable behavior, so the recommandation is to always set a resource plan when you set manually CPU_COUNT. Here is another reason for such…

 
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Oracle Team

Adaptive Plan: How much can STATISTICS COLLECTOR buffer?

By | Database Administration & Monitoring | 7 Comments

By Franck Pachot . The 12c adaptive plan prepares two join methods (Hash Join and Nested Loop), actives the one that has the better cost for the estimated cardinality and computes the point of inflection in cardinality estimation where the best cost changes to the other join method. At execution time, rows are buffered by a STATISTICS COLLECTOR operation in order to see if the point of inflection is reached. If it doesn’t, the plan…

 
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