Oracle database management, tutorials, scripts, coding, programming and tips for database administrators
If you’re using invisible indexes, they may not be entirely ‘invisible’ to the optimizer. Read on to see why.
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 can return negative results; read on to see why and what can be done to work around the issue.
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.
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.
When using Oracle 126.96.36.199 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.
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 may be more 'expensive' than the Oracle optimizer reports; read on to see why.
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.
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.
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.
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 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.
In Oracle 188.8.131.52 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.
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.