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Oracle database management, tutorials, scripts, coding, programming and tips for database administrators


Skipping Schema DML in an Oracle 11.2 Logical Standby Database 10/13/2014

Skipping DML for one or more schemas isn't as simple as you might think.  Read on to see what steps are necessary to avoid ORA-02149 errors and keep the logical standby synchronized.

Oracle: Can a NULL sql_id Use CPU? 09/29/2014

Oracle can exhibit 'strange' behavior with the sql_id values in V$SESSION, but just because the sql_id is NULL that doesn't mean Oracle isn't processing a long-running statement.

Oracle Bloom Filters 09/11/2014

In Oracle releases 10.2.0.x and later join processing can be made more efficient by the use of Bloom filters, primarily to reduce traffic between parallel query slaves. Read on to learn more.

Oracle: Is Parallel Really Necessary? 08/25/2014

You're running processes in parallel; is it really faster?  Sometimes it may not be; read on to see why parallel processing may be creating more work than you'd expect.

Oracle: Getting The Starting Date Of A Week Using Week Number 08/14/2014

Week numbering schemes are interesting and getting the starting date based on that number is even more so. Read on to see what schemes there are and if you can, indeed, get the starting date you expect.

Understanding Hugepages in Oracle Database 07/28/2014

Large Oracle instances running on Linux can benefit from using hugepages.  Read on to see what hugepages are and how they help Oracle run better.

Exadata: When A Smart Scan Isn't 07/17/2014

Exadata is known far and wide for Smart Scans, but sometimes Oracle can do better without one.  Read on to see how to know when Oracle decided to not continue with a Smart Scan.

Increase DSS Performance by 100x and OLTP by 2x: Switch to Oracle 12c 07/10/2014

The next big thing after Exadata is the new Oracle 12c Database In-memory feature, which will dramatically improve database performance for analytical queries and OLTP without application re-coding.

Performance -- It May Not Be The Database 06/30/2014

When performance suffers it's likely the DBA who gets the blame, but it may not be the database that's at fault.  Read on to see what other factors can affect performance and how to identify what is causing the slowdown.

"The Chain Gang", a Riveting Tale of Chained and Migrated Rows in Oracle 06/12/2014

Chained and migrated rows in an Oracle database can adversely affect I/O performance, especially Exadata.  Read on to discover how these rows are generated and what you may be able to do to correct the situation.

Are There Safeguards to Prevent the DBA from Dropping a Table? 05/27/2014

How do you ensure that the DBA doesn't, or can't, drop a table accidentally? Oracle has at least two ways to ensure that a table cannot be accidentally dropped but there are some limitations to those methods. David Fitzjarrell looks at those methods to see which one works for the DBA account.

Modifying a Primary Key Index in Oracle 11.2.0.x 05/08/2014

Some business decisions may need to be redone, like making a non-unique primary key index unique.  In Oracle 12c it's a simple task, but in Oracle 11.2. and earlier it's a bit more involved but still possible.  Read on to see how this can be done.

Oracle Database: Where’s My Space? 04/28/2014

Your developer has deleted a ton of data to help you free up space in the OS. Right? Wrong. Find out how to get all that free space in a table reflected all the way out to the operating system.

Oracle 11.2 Outer Join And Index Issue 04/10/2014

With a product as complex as Oracle some bugs are bound to be present. Some of these bugs are show-stoppers, and others aren't, but it does teach you to pay careful attention to the results a query delivers. Even though queries are syntactically and logically correct you can't be certain that Oracle won't do something 'behind the scenes' that can produce the wrong answer.

An RMAN Catalog: Right or Wrong? 03/31/2014

Do you really need an RMAN catalog to successfully recover your Oracle database? There are those that think so -- but they would be wrong. Read on to find out what you need to recover your database without a catalog.

Oracle Archives

Latest Forum Threads
Oracle Forum
Topic By Replies Updated
Oracle Data Mining: Classification jan.hasller 0 July 5th, 07:19 AM
Find duplicates - Unique IDs Lava 5 July 2nd, 08:30 AM
no matching unique or primary key rcanter 1 April 25th, 12:32 PM
Update values of one table based on condition of values in other table using Trigger Gladiator 3 February 29th, 06:01 PM