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Category Archives: Oracle

Oracle Team

RAC Attack! next month 12c in Las Vegas

By | Database management, Oracle | No Comments

By Franck Pachot . RAC is the most complex installation you can have for an oracle database. A RAC DBA is involved not only on database, but storage, network, and system as well. It involves also the application in order to be sure that the application service can follow the database service high availability. It’s also brings every database skills to the highest level: small contention on single instance database can become a big bottleneck…

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Oracle Team

Query the Enterprise Manager collected metrics

By | Database management, Oracle | 5 Comments

By Franck Pachot . Enterprise Manager (Cloud Control for example) gathers a lot of metrics. You can display them from the GUI, but you can also query the SYSMAN views directly. Today, I wanted to get the history of free space in an ASM disk group for the previous week. Here is how I got it. Enterprise Manager metrics are aggregated in MGMT_METRICS_1HOUR (granularity 1 hour, retention 1 month) and MGMT_METRICS_1DAY (granularity 1 day, retention…

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Oracle Team

12c online statistics gathering and startup restrict

By | Database management, Oracle | One Comment

By Franck Pachot . I’ve written about 12c online statistics gathering in a UKOUG OracleScene article. My opinion is clear about it: you sill need to gather stale stats afterwards or you have mising, stale and inconsistent object statistics. This post is about cases where online statistics gathering does not occur (and are not documented) – which is another reason why we can’t rely on it. The case where it works You can check on…

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Oracle Team

How to set NLS for SQL Developer

By | Database management, Oracle | No Comments

By Franck Pachot . I’m using Oracle SQL Developer 4.1 Early Adopter for a while and I like it. That version comes with a command line (in beta) which goal is to be fully compatible with sqlplus but running in java, and having a lot more features. Becuse it’s connecting with thin java driver by default, it doesn’t use NLS_LANG. It’s java. It’s unicode. So here is how to set the language and characterset with…

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Oracle Team

Is CDB stable after one patchset and two PSU?

By | Database management, Oracle | 7 Comments

By Franck Pachot . There has been the announce that non-CDB is deprecated, and the reaction that CDB is not yet stable. Well. Let’s talk about the major issue I’ve encountered. Multitenant is there for consolidation. What is the major requirement of consolidation? It’s availability. If you put all your databases into one server and managed by one instance, then you don’t expect a failure. When 12c was out (and even earlier as we are…

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Oracle Team

OracleText: deletes and garbage

By | Database management, Oracle | No Comments

By Franck Pachot . In the previous post we have seen how the OracleText index tables are maintained when new document arrives: At sync the new documents are read up to the available memory and words are inserted in the $I table with their mapping information. Now we will see how removed documents are processed. We will not cover updates as their are just delete + insert. Previous state Here is the state from the…

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Oracle Team

OracleText: inserts and fragmentation

By | Database management, Oracle | No Comments

By Franck Pachot . I plan to write several posts about OracleText indexes, which is a feature that is not used enough in my opinion. It’s available in all editions and can index small text or large documents to search by words. When you create an OracleText index, a few tables are created to store the words and the association between those words and the table row that contains the document. I’ll start to show…

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Oracle Team

Never gather WORKLOAD stats on Exadata…

By | Database management, Oracle | 3 Comments

By Franck Pachot . 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…

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Oracle Team

Oracle multitenant dictionary: rowcache

By | Database management, Oracle | No Comments

By Franck Pachot . I’ve not finished with my investigation on 12c multitenant dictionary. Here, I’m checking how metadata links are managed by the dictionary cache (aka rowcache). As I did previously, I’ll create a metadata link function in my lab environment (this is not for production. For the moment metadata/object links are supported only for oracle objects). SQL> connect / as sysdba Connected. SQL> create or replace function DEMO_MDL_FUNCTION sharing=metadata 2 return varchar2 as…

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Oracle Team

IOUG Collaborate #C15LV

By | Operation systems, Oracle | No Comments

By Franck Pachot . The IOUG – Independant Oracle User Group – has a great event each year: the COLLABORATE. This year it’s in April 12-16, 2015 at The Mandalay Bay Resort & Casino in Las Vegas. I’ll be a speaker and a RAC Attack Ninja as well.  IOUG COLLABORATE provides all the real-world technical training you need – not sales pitches. The IOUG Forum presents hundreds of educational sessions on Oracle technology, led by…

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