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