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Jan 11 2021
Christian Weinfurtner

Oracle 21c: Blockchain Tables

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

Oracle Blockchain Tables With Oracle Database 20c/21c the new feature Oracle Blockchain Tables has been introduced. Blockchain Tables enable Oracle Database users to create tamper-resistant data management without distributing a ledger across multiple parties. Database security can be improved by using Blockchain Tables to avoid user fraud and administrator fraud as well. One of the main characteristics of Oracle Blockchain Tables is that you can only append data. Table rows are chained using a cryptographic…

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Jan 05 2021
Frank Bléger

How to quickly download the new bunch of 21c Oracle Database documentation?

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

Last month, Oracle released its new 21c version of the database documentation. At that time, I was looking for a quick mean to get all the books of this so-called 21c Innovation Release. I could remember I used a script to get them all in one run. Quick look at google, remembered me I used the one from Christian Antognini which hasn’t been refreshed for a while. In this blog, I will provide you the…

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Dec 29 2020
Franck Pachot

Optimizer Statistics Gathering – pending and history

By | Oracle | No Comments

By Franck Pachot . This was initially posted to CERN Database blog on Wednesday, 12 September 2018 where it seems to be lost. Here is a copy thanks to web.archive.org Demo table I create a table for the demo. The CTAS gathers statistics (12c online statistics gathering) with one row and then I insert more rows: 10:33:56 SQL> create table DEMO as select rownum n from dual; Table DEMO created. 10:33:56 SQL> insert into DEMO…

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Dec 27 2020
Franck Pachot

Password rolling change before Oracle 21c

By | Oracle | One Comment

By Franck Pachot . You may have read about Gradual Password Rollover usage from Mouhamadou Diaw and about some internals from Rodrigo Jorge. But it works only on 21c which is only in the cloud, for the moment, in Autonomous Database and DBaaS (but here I’ve encountered some problems apparently because of a bug when using SQL*Net native encryption). But your production is not yet in 21c anyway. However, here is how you can achieve…

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Dec 19 2020
Franck Pachot

Oracle SPD status on two learning paths

By | Oracle | No Comments

By Franck Pachot . I have written a lot about SQL Plan Directives that appeared in 12c. They were used by default and, because of some side effects at the time of 12cR1 with legacy applications that were parsing too much, they have been disabled by default in 12cR2. Today, there are probably not used enough because of their bad reputation from those times. But for datawarehouses, they should be the default in my opinion….

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Dec 15 2020
Franck Pachot

Efficiently query DBA_EXTENTS for FILE_ID / BLOCK_ID

By | Oracle | No Comments

By Franck Pachot . This was initially posted to CERN Database blog on Thursday, 27 September 2018 where it seems to be lost. Here is a copy thanks to web.archive.org Did you ever try to query DBA_EXTENTS on a very large database with LMT tablespaces? I had to, in the past, in order to find which segment a corrupt block belonged to. The information about extent allocation is stored in the datafiles headers, visible though…

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Dec 14 2020
Franck Pachot

Oracle write consistency bug and multi-thread de-queuing

By | Oracle | 3 Comments

By Franck Pachot . This was initially posted on CERN Database blog where it seems to be lost. Here is a copy thanks to web.archive.org Additional notes: – I’ve tested and got the same behaviour in Oracle 21c – you will probably enjoy reading Hatem Mahmoud going further on Write consistency and DML restart Posted by Franck Pachot on Thursday, 27 September 2018 Here is a quick test I did after encountering an abnormal behavior…

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Oct 15 2020
Christian Weinfurtner

Upgrade to Oracle 19c – performance issue

By | Database Administration & Monitoring, Database management, Oracle | One Comment

In this blog I want to introduce you to a workaround for a performance issue which randomly appeared during the upgrades of several Oracle 12c databases to 19c I performed for a financial services provider. During the upgrades we ran into a severe performance issue after the upgrades of more than 40 databases had worked just fine. While most of them finished in less than one hour, we run into one which would have taken…

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