A few years back, some colleagues of mine were bemoaning the fact that functions created as DETERMINISTIC weren’t actually implemented as such in 10.2. Just to be clear, this is no longer the case with Oracle 11. DETERMINISTIC functions actually are deterministic:
Every now and then, I get involved in interviewing Oracle developers when we’re specifically after “performance” skills. I ask a range of fairly expansive questions but I always ask if they know what Scalar Subqueries are and why they can deliver amazing performance benefits. Not many people seem to have heard of Scalar Subqueries are and even fewer are aware of the caching benefits.
A friend of mine who’s work and attitude towards Oracle performance and architecture I respect has just started blogging, so I thought I would give him a mention. Dave Webster, welcome to the world of blogging. I know from some discussions with Dave about blogging that he has a lot of things he wants to [...]
SQL*Plus TIMING is a handy little utility that you can use to do a performance analysis on any commands or blocks run during a period. It is different from the SET TIMING command which is used to display timing data after each SQL command or PL/SQL block you run. Here is an example: TIMING SHOW [...]
How to compile new oci8 in PHP source?
Flashback database is great alternative for incomplete recovery because it is much less time consuming in some cases. You can find in documentation nice explanations how flashback database works so I won’t concentrate much on theory.
In this blog post I will perform simple demo case of point in time recovery using flashback database feature.
Database must be in ARCHIVELOG mode and FLASHBACK should be enabled.
Contrary to popular believe Oracle latches were significantly evolved through the last decade. Not only additional statistics appeared (and disappeared) and new (shared) latch type was introduced, the latch itself was changed It is interesting to see how the latch was organized in the past and contemporary versions. To see the latch in-memory seems hard, [...]
When using tables with large amounts of rows and especially after a lot of rows have been deleted from such a table, reorganizing the table may improve the performance of the table.
Oracle knows two types of table reorganizations.
Below the two methods are explained.
Rebuilding the table by means of recreating it
As of this afternoon, version 18.104.22.168.1 of Oracle’s Exadata storage server software, is out in the wild. This is the first publicly available version of the 22.214.171.124 branch, a major release including a full OS image with an update to Oracle Enterprise Linux 5.5. A number of bugs causing cell server crashes and [...]