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

Oracle

Is Your Oracle Invisible Index REALLY Invisible? 07/25/2016

If you’re using invisible indexes, they may not be entirely ‘invisible’ to the optimizer. Read on to see why.

Returning The Actual DOP When Using Oracle’s Auto Degree Of Parallelism 07/14/2016

Without having an execution plan it’s difficult to know the degree of parallelism Oracle has selected.  Read on to see how that can be reported.

Oracle’s REMAINDER Function: The Result Isn’t Always Correct 06/27/2016

Oracle’s REMAINDER function can return negative results; read on to see why and what can be done to work around the issue.

Oracle's Calibrate_io Procedure: Why You Should Use It 06/13/2016

Oracle's calibrate_io procedure populates the data dictionary with disk 'performance' data to give the optimizer a fighting chance at a decent plan.  Read on to see why the data it generates may not be the most accurate with respect to performance.

Mutating Table Error In Oracle: Why It Happens And What You Can Do About It 05/31/2016

There are a lot of 'explanations' offered for the ORA-04091 error; read on to find out what is really going on and  how to address the situation.

Oracle SRVCTL Issue in 11.2.0.4 05/12/2016

When using Oracle 11.2.0.4 in a Grid configuration the srvctl utility can change the group on the Oracle executables, creating problems with locating the spfile and with disk access.

Re-thinking SQL Queries Using Sets in Oracle 04/28/2016

Sometimes it's good to re-think how to write a query; set operations can provide performance benefits over 'straight SQL'.  Read on to see an example of this in action.

Deletes In Oracle: More 'Costly' Than You Think 04/21/2016

Deletes may be more 'expensive' than the Oracle optimizer reports; read on to see why.

Oracle 12c Table Point-in-time Recovery 03/28/2016

There may be times when you need to recover a single table and flashback isn't configured and the recycle bin is turned off. Using RMAN in Oracle 12c it's possible to restore and recover a single table. Read on to see how it's done.

Partition Limits In Oracle 03/14/2016

Partitioning can be a real asset when used properly, as long as you don't run afoul of the maximum number of partitions Oracle will allow.  Read on to learn the maximum number of partitions and discover some of the errors you can see if you try to exceed the limit.

The One 'Security' Feature in Oracle You Probably Shouldn't Use 02/29/2016

Oracle offers a number of security-related settings, but one could definitely create more harm than good.  Read on to see which parameter that is, and why.

Unique Records In Oracle 02/11/2016

There are several ways to ensure unique records in an Oracle table, but are some better than others?  Read on to see how each method compares.

Oracle's ANSI Join Syntax Can Result In Wrong Results 01/21/2016

Oracle can still have issues with ANSI join syntax, producing sub-optimal translations and possibly wrong results.  Read on to see how Oracle processes ANSI join syntax and how that translation process can create some problems.

Memory Leak in 11.2.0.1 on AIX: Shared Cursors Are Not Behaving 01/11/2016

In Oracle 11.2.0.1 shared cursor memory in some subpools can increase dramatically over time, resulting in having to restart the database.  Read on to see how this was discovered and how to check the subpool memory allocations.

Function-based Index on LOB Columns and Oracle's SQL*Loader 12/28/2015

SQL*Loader can fail to load LOB data when function-based indexes are present on the LOB columns.  Read on to learn more and work around the issue.

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