#oug_ire
07.03.2016

OUG Ireland 2016

I was second time at the conference organized by UKOUG but this time I had a pleasure to be among the speakers ­čÖé To reach the level set by other speakers was impossible – but trying it gives a lot of fun. Since I did a live demo and I didn’t have any slides – […]


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EXADATA
11.02.2016

Exadata – direct path write temp and flash disks

Some time ago one of my students asked me if temp segments are being written to flash disks on Exadata… Well I wasn’t sure ­čÖé But recently I had some time to check it. Let’s create some query that will generate temp segment: Great. Now we have to do some tracing at the cell servers […]


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12c & external tables
10.02.2016

How to list files from directory using external table in 12c

I’ve wrote about privilege escalation with external tables in this post: https://blog.ora-600.pl/2014/12/23/simple-technics-of-privilege-escalation-part2-dbasysdba/ This time we will try to list all files within directory object, to which we have no EXECUTE privs. This is possible due to great new feature of database 12c that allows to use metacharacters to match multiple files in external table. I […]


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M7
08.02.2016

Sparc M7 vs Intel and P8

I had a pleasure to work with my colleagues from Oracle – Rados┼éaw Kut and Krzysztof Marciniak – at comparing the performance of In-Memory queries between Sparc M7, Intel┬« Xeon┬« X5670 and Intel┬« Xeon┬« E5-2699. You can find results of our findings in this presentation: https://www.oracle.com/webfolder/s/delivery_production/docs/FY16h1/doc17/DB12c-on-SPARC-M7.pdf Following their methodology I’d like to present appropriate results […]


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M7
27.01.2016

Oracle SPARC M7 – tracing DAX with DTrace and busstat

Thanks to Oracle I had a possibility to test the new Sparc M7 with DAX coprocessors to boost In-Memory performance. You can read about it here and here My first thought was – how to check if and when the DAX coprocessors are being used? When you have a POC for Exadata, you want to […]


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tuning
13.01.2016

oracle dblinks – performance considerations

Let’s imagine the following situation – you have a table called EMPLOYEES_TMP which is a global temporary table with a variable number of rows – totally nondeterministic. And there is a query which runs very often to compare primary key values between this table and a remote one (which is basically the same but not […]


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Mierzymy wysoko z WOŚP!
10.01.2016

Mierzymy wysoko z WOŚP!

ORA-600 i IT School wspieraj─ů XXIV fina┼é Wielkiej Orkiestry ┼Üwi─ůtecznej Pomocy. Nasze po┼é─ůczone si┼éy dewelopersko-administratorskie przygotowa┼éy aplikacj─Ö, za pomoc─ů kt├│rej b─Ödziecie mogli licytowa─ç z┼éote serduszka oraz karty u┼╝ywaj─ůc do tego celu komputer├│w lub urz─ůdze┼ä mobilnych. Wejd┼║cie i zalicytujcie na: https://licytacja.wosp.org.pl/. Cieszymy si─Ö, ┼╝e mo┼╝emy mierzy─ç wysoko razem z WO┼ÜP. W tym roku pieni─ůdze zostan─ů przeznaczone […]


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12c
17.12.2015

Oracle 12c – internals of threaded execution

At UKOUG Tech’15 (Super Sunday) there was a session called "12c: A Closer Look at the Multi-Process Multi-Threaded Model for Oracle on Linux/Unix" by Markus Flechtner. Since then I can’t stop thinking about the performance of this feature. Why Oracle decided to provide it? I did some tests regarding sort operations and threaded execution was […]


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12c
29.10.2015

Oracle 12c: PRAGMA UDF – the truth

Let’s check, why PRAGMA UDF makes execution faster, then regular function. C function responsible for calling a PL/SQL code from SQL is called "plsql_run": Now let’s try to create a new HR session and create a simple function which will multiple values by 2: From other terminal I will connect to the HR session with […]


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