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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SECURITY
11.10.2015

Secure your database (part 1)

I’ve already showed you, how to escalate privileges in Oracle Databases. http://blog.ora-600.pl/2013/04/02/privilege-escalation-in-oracle-11gr2-part1/ http://blog.ora-600.pl/2014/12/23/simple-technics-of-privilege-escalation-part2-dbasysdba/ The question is – how to secure your database, if you don’t have EE or possibility to buy Oracle Database Vault or Oracle Advanced Security. Well – there’s always a DBA creativity 😉 For example – if you want to secure the […]


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[PL] Browar z Wyrocznią
04.09.2015

Jak smakuje Browar z Wyrocznią

I było tak, że 31 dnia miesiąca sierpnia roku 2015, spotkali się entuzjaści Wyroczni w posiadłości AVIVA. I było tak, że dzierżąc kufle – po brzegi browarem wypełnione – zasiadło wielu aby posłuchać kilku, którzy chcieli się przemyśleniami swoimi podzielić. I stało się tak, że admin przepijał do dewelopera a deweloper do admina i pospołu dyskusja toczyła się wartka a […]


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RICO
03.09.2015

RICO

I’ve started the project called RICO – the tool, written in C++ for last resort data recovery. It can be used to extract data from corrupted datafiles and dump them in the form of text files. It is in the early development stage right now and the functionalities are narrowed to: Dump regular and partitioned […]


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12C
03.09.2015

12c – SQL plan directives

One of the new CBO features in database 12c is "sql plan directives". The main purpose of this functionality is to deliver better adaptive plans if object statistics does not reflect the reality. Quoting after documentation During SQL execution, if a cardinality misestimate occurs, then the database creates SQL plan directives. During SQL compilation, the […]


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I/O
17.07.2015

db file scattered read – MBRC and ASYNC IO on linux

Recently one of my students asked me if there is any correlation between the AU size in ASM diskgroup and parameter db_file_multiblock_read_count. I made some tests but results are very strange. I have 4 same tables, located in 4 different diskgroups: All tables are smaller then a hidden parameter "_small_table_threshold" so table access full on […]


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12c
25.05.2015

12c: duplicate pluggable database without READ ONLY mode

At the beginning we have to prepare parameter file for the new instance Start the instance in nomount Since I want to duplicate the database in active mode I will register it in LISTENER. To achieve this I have to add the following lines to the listener.ora Now we can perform active database duplication with […]


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ASM
14.05.2015

DBA: migrate database to ASM

Let’s try to migrate database to ASM diskgroup without big maintenance window. I have database and ASM (11.2.0.4) – the database is prepared to migration: We will use recoverable copy of database to migrate to ASM. The first run of this script will create copy of datafile on ASM: Subsequent executions of this script will […]


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ASM
14.05.2015

Install ASM manually using response file

I have configured two devices for ASM – one with ASMLib and one with UDEV: I have downloaded 11.2.0.4 grid infrastructure binaries and prepared response file: Of course in production environment you have set different groups for security reasons. If you think that you can ignore security, read my articles regarding privilege escalations: http://blog.ora-600.pl/category/oracle/security/ With […]


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12c (Spatial)
03.05.2015

12c: Spatial Vector Acceleration

There is a new feature in Oracle Spatial 12c, called "Spatial Vector Acceleration". According to Oracle: One of the most notable improvements with Oracle Spatial and Graph 12c can be seen in performance increases in vector data operations. Enabling the Spatial Vector Acceleration feature (available with the Spatial option) dramatically improves the performance of commonly […]


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RAC: tips&tricks
17.04.2015

RAC: CHANGE IP OF CLUSTER INTERCONNECT

In this article I will show how to change IP address of cluster interconnect. First we have to define new address of the cluster interconnect before we change network settings. And now stop all cluster resources on both nodes Now we can change cluster interconnect ips Now we can start init cluster resources on both […]


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