Oracle database management, tutorials, scripts, coding, programming and tips for database administrators
In Oracle 11.2 using analytic functions can generate 'interesting' cardinality values that are far larger than they should be. Read on to see just how far off those values can be.
Overflow data in an index-organized table is usually put in its own tablespace. Sometimes it isn't; read on to see what overflow data is and how to change where it's located.
Odd errors can result in odd 'solutions', and Oracle has one for the MERGE statement. Read on to see what it is and what it fixes.
Oracle provides several levels of compression, with BASIC compression requiring no additional license cost. Read on to find out how this level of compression works and what you may expect when using it.
Using parallel query can improve performance in some cases but AWR reports can report too much elapsed time when they are used. Read on to see why and how you can get the actual elapsed time in those cases.
Some problems can appear to be more difficult than they are. Read on to see how changing how you think about a problem can open up new ways to solve it.
Performance is the watchword with a database and indexes can be a major part of that performance equation. Oracle provides the optimizer_index_cost_adj parameter but do you REALLY need to set it differently than the default? Read on to see what may happen when you do.
For business executives looking to save on information technology costs, it may seem like a win-win scenario in Oracle database environments to transition from Oracle Enterprise to Standard Edition. However, executives making this decision may not always be aware of or truly understand how transitioning from Enterprise to Standard Edition will affect the delivery of critical IT services, ultimately creating the potential to impact end user efficiency and revenue.
Adaptive cursor sharing is a great feature that can tailor execution plans to bind variable values. Read on to see how it behaves when query order is reversed and if it chooses 'bad' execution plans.
Oracle offers Deferred Segment Creation for tables and indexes, which allows users with no access to a tablespace to create tables and indexes successfully. Read on to see why this is a problem.
Bloom filters can improve performance in recent Oracle releases, but Oracle 22.214.171.124 provides the In-Memory Database option and using that configuration can improve performance even further. Read on to see how the in-memory option is configured and the performance it provides.
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 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.
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.
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.