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What is cloning? Cloning is a process of copying an existing installation to a different server or location. Cloning is similar to an Oracle installation except Oracle universal installation performs the actions in a special mode called “clone mode”. Starting from 10g onwards, Oracle supports cloning and users can easily clone existing Oracle installations. The source and destination servers should… Continue Reading →

10g, 11g, All Things Oracle Full Articles, Database Administration, Database Development

In the final part of this series I want to cover one last source of Parallel Execution Skew: Skew caused by Outer Joins. If you have Outer Joins where the majority of foreign key values is NULL, this can lead to the following symptoms: From a processing point of view for a parallel outer join, the NULL value in the foreign… Continue Reading →

10g, 11g, 12c, All Things Oracle Full Articles, Database Administration, Database Development, Oracle Database, Performance Tuning, Troubleshooting

In this part of the series we will have a look at different approaches to how Parallel Execution Skew can be addressed via manual re-writes of an affected query. Let’s have a look at a couple of options. Approach 1: Mimic the new 12c skew aware feature Looking at the new 12c special skew aware distribution feature that I’ve introduced… Continue Reading →

10g, 11g, 12c, All Things Oracle Full Articles, Oracle Database, Performance Tuning, Troubleshooting

After providing a baseline for Parallel Execution working as expected in the introduction of this series, in this part I’ll demonstrate how things can go wrong with the work distribution. A Simple Example Of Parallel Execution Skew One common source of Parallel Execution Skew is a skewed foreign key, which means that the value distribution of the foreign key column… Continue Reading →

10g, 11g, 12c, All Things Oracle Full Articles, Oracle Database, Performance Tuning, Troubleshooting

Admit that your own private Mount Everest exists. That is half the battle. – Hugh Macleod Other options In the example we used pretty much the minimum number of parameters to make it work. There are more parameters and options available. For example UPDATE_CHECK. This does pretty much the same as WITH UPDATE CHECK in views. If you insert or… Continue Reading →

10g, 11g, 12c, 8i, 9i, All Things Oracle Full Articles, Database Development, Oracle Database, PL/SQL

Views When working with views you have several options to hide some of the data. In the article on views I have told you about the way to hide columns from the table. By adding a predicate (where clause) to the view, you can restrict the rows a user sees. This would imply creating different views for different (groups of)… Continue Reading →

10g, 11g, 12c, 8i, 9i, All Things Oracle Full Articles, Database Development, Oracle Database, PL/SQL

Views

Patrick Barel on 05 June 2013 with 1 comments

Success always occurs in private and failure in full public view. – Unknown When working with views you have several options to hide some of the data. Of course there is the possibility not to select certain columns of data in the view. This way, the user of the view doesn’t even have to know this column even exists. You… Continue Reading →

10g, 11g, 12c, 8i, 9i, All Things Oracle Full Articles, Oracle Database, PL/SQL

Technology is dominated by two types of people: those who understand what they do not manage, and those who manage what they do not understand – Putt’s Law We are always working with data and their datatypes. In the tables we constrain the data by their datatype. For instance, we create a price column of type NUMBER(4,2) telling the database… Continue Reading →

10g, All Things Oracle Full Articles, Database Development, PL/SQL, Troubleshooting, Uncategorized

In part 1 I explained how to duplicate a single instance database using RMAN. This article will focus on converting the single instance to RAC. 2. Convert Single instance to RAC We have migrated the database successfully from Non-ASM to ASM using RMAN; the database is still running as single instance.  Now we need to convert the single instance database… Continue Reading →

10g, 11g, All Things Oracle Full Articles, Application Development, Database Administration, Oracle Database, Uncategorized

This article is for users of Oracle Database version 10g+ who want to convert their Oracle single instance database to RAC.  I will provide detailed procedure for converting non-RAC database to RAC and we will use Oracle Automatic storage management (ASM) as shared storage. In general, if the database is small then you can consider installing a new RAC database… Continue Reading →

10g, 11g, All Things Oracle Full Articles, Database Administration, Oracle Database