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Christian Weinfurtner

Upgrade to Oracle 19c – performance issue

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

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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Franck Pachot

CLUSTER

By | Oracle | No Comments

By Franck Pachot . Statistically, my blog posts starting with a single SQL keyword (like COMMIT and ROLLBACK) in the title are not fully technical ones, but about moves. Same here. It is more about community engagement, people sharing. And about a friend. And clusters of course… In 2020 because of this COVID virus, we try to avoid clusters of people. And everybody suffers from that in the community because we have no, or very…

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Franck Pachot

Oracle ADB from a Jupyter Notebook

By | Database Administration & Monitoring, Oracle | No Comments

By Franck Pachot . My first attempt to connect to an Oracle database from a Jupyter Notebook on Google Colab was about one year ago: https://medium.com/@FranckPachot/a-jupyter-notebook-on-google-collab-to-connect-to-the-oracle-cloud-atp-5e88b12282b0 I’m currently preparing a notebook as a handout from my coming SQL101 presentation where I start with some NoSQL to discover the benefits of RDBMS and SQL. I’m running everything on the Oracle Database because it provides all APIs (NoSQL-like key-value, with SODA, documents with OSON, and of course…

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Marc Wagner

How to synchronize the appliance registry metadata on an ODA?

By | Database Administration & Monitoring, Oracle | No Comments

Databases administration on a Bare Metal ODA will be done as root user by running odacli commands : odacli create-database to create a database odacli upgrade-database to upgrade a database between major releases odacli move-database to move databases from one Oracle home to another of the same database version odacli update-dbhome to update a specific RDBMS home to the latest patch bundle version etc… The odacli commands will do the needful and at the end…

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Clemens Bleile

Oracle DML (DELETE) and the Index Clustering Factor

By | Oracle | No Comments

As a consultant working for customers, I’m often in the situation that I have an answer to a problem, but the recommended solution cannot be implemented due to some restrictions. E.g. the recommendation would be to adjust the code, but that is not feasible. In such cases you are forced to try to help without code changes. Recently I was confronted with the following issue: A process takes too long. Digging deeper I could see…

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Franck Pachot

Troubleshooting performance on Autonomous Database

By | Oracle | No Comments

By Franck Pachot . On my Oracle Cloud Free Tier Autonomous Transaction Processing service, a database that can be used for free with no time limit, I have seen this strange activity. As I’m running nothing scheduled, I was surprised by this pattern and looked at it by curiosity. And I got the idea to take some screenshot to show you how I look at those things. The easiest performance tool available in the Autonomous…

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Jérôme Dubar

Oracle Database Appliance and CPU speed

By | Database Administration & Monitoring, Development & Performance, Hardware & Storage, Operation systems, Oracle | No Comments

Introduction A complaint I heard from customers about ODA is the low core speed of the Intel Xeon processor embedded in the X8-2 servers: Intel(R) Xeon(R) Gold 5218 CPU @ 2.30GHz. 2.30GHz only? Because of its comfortable number of cores (16 per processor), the cruise speed of each core is limited. Is it a problem compared to a home made server with less cores? Why clock speed is important? As you may now, the faster…

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Clemens Bleile

Merge-Statement crashes with ORA-7445 [kdu_close] caused by Real Time Statistics?

By | Oracle | No Comments

In a recent project we migrated an Oracle database previously running on 12.1.0.2 on an Oracle Database Appliance to an Exadata X8 with DB version 19.7. Shortly after the migration a merge-statement (upsert) failed with an ORA-07445: exception encountered: core dump [kdu_close()+107] [SIGSEGV] [ADDR:0xE0] [PC:0x1276AE6B] [Address not mapped to object] [] The stack looked as follows: kdu_close – updThreePhaseExe – upsexe – opiexe – kpoal8 – opiodr – ttcpip – opitsk – opiino – opiodr…

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Franck Pachot

The myth of NoSQL (vs. RDBMS) “a simpler API to bound resources”

By | NoSQL, Oracle | No Comments

By Franck Pachot . NoSQL provides an API that is much simpler than SQL. And one advantage of it is that users cannot exceed a defined amount of resources in one call. You can read this in Alex DeBrie article https://www.alexdebrie.com/posts/dynamodb-no-bad-queries/#relational-queries-are-unbounded which I take as a base for some of my “Myth of NoSQL vs RDBMS” posts because he explains very well how SQL and NoSQL are perceived by the users. But this idea of…

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Clemens Bleile

Oracle ASH SQL_PLAN_LINE_ID in adaptive plans

By | Oracle | No Comments

There are several methods to find out where time is spent in an execution plan of a query running in an Oracle database. Classical methods like SQL Trace and running a formatter tool like tkprof on the raw trace, or newer methods like SQL Monitor (when the Tuning Pack has been licensed) or running a query with the GATHER_PLAN_STATISTICS-hint (or with statistics_level=all set in the session) and then using DBMS_XPLAN.DISPLAY_CURSOR(format=>’ALLSTATS LAST’). However, what I often…

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