When working with Oracle GoldenGate, understanding the System Change Number (SCN) is important. The SCN is an internal number maintained by the database that keeps track of the changes made to the database for recovery purposes. The SCN is also important when working with Oracle GoldenGate. In many environments, instantiation of Oracle GoldenGate environments require knowing where to start the replicat from.
To find the current SCN for the database, Oracle has made this pretty (more...)
Chained and migrated rows in an Oracle database can seriously impact I/O performance, especially with Exadata. In a ‘normal’ Oracle database [read that as "non-Exadata, non-ASM" database] chained rows, in small numbers where that usually means 1% or less of the total rows in a table, are generally a nuisance. The performance hit they generate in such a situation is small and may not even be noticed by the end users. Add more chained/migrated rows (more...)
Editor’s Note: Here’s a post from newish ‘Lab member, Tony. Enjoy, and maybe if you’re nice in comments, he’ll write more. Or not, we won’t know until we know.
The ideas flying, crawling, walking, and slithering around us in the sunny windy San Francisco Bay setting made for an enjoyable, educational, and truly inspirational experience. O’Reilly Solid conference: Software/Hardware/Everywhere was last week and with it, the future finally materialized. Wearables, robots, new materials, new (more...)
Editor’s note: Here’s another post from friend of the ‘Lab and colleague, John Cartan. When John reached out, offering a review of the Narrative Clip (neé Memento), I jumped at the opportunity to read and publish his thoughts, and not just because I value his insights.
Over the past 12 months, the chatter about wearables (glasses, watches, bands, clothing, material) has become too loud to ignore. It almost seems like manufacturers will force consumers to like wearables, like it or not.
There are good uses for wearables, and one of the most common is the fitness tracker.
Although I haven’t worn one myself until recently, I’ve been around lots of people who have, e.g. my wife had an early FitBit, Noel (more...)
Friend of the ‘Lab, Bob Rhubart (@otnarchbeat) recently recorded a segment with our own Noel (@noelportugal) and Sarahi Mireles (@sarahimireles), a UX developer from our Mexico Development Center.
The topic was wearables, but I only know this because they told me. Google Translate wasn’t very helpful, unless “Manos libres y vista al frente: Con el futuro puesto” means “Handsfree and front view: With the future since.”
Some of the strangest ideas (to me, anyway) can be found in the depths of PL/SQL code, be it a package, a procedure, a function or an anonymous block. Granted, such decisions may be the result of budgetary considerations which prevented a more robust and reliable application design. I was looking at some code just recently that made me scratch my head in wonder and disbelief. Let’s look at a similar piece of PL/SQL that (more...)
A recent IT-related survey had in its list of questions one rather interesting offering:
“Are there any safeguards preventing the DBA from accidentally dropping a table?”
That is probably not a commonly considered aspect of data security however it is an issue that should be voiced and addressed. How do you ensure that the DBA doesn’t, or can’t, drop a table accidentally? Oracle has at least two ways to ensure that a table cannot (more...)
While investigating a question on returing unmatched rows between two tables I set up an example where both tables had indexes which could be used to speed up the query and hopefully return the result set in less time than required for a full table scan. To my surprise when the index was used on the table with the missing record the query returned no rows. Not understanding this behavior (as I KNEW there was (more...)
Indexes can be very useful tools to improve query performance, but it can be difficult to test indexes in an environment that exactly mirrors production. Although not the preferred method, Oracle offers in 11.2 and later releases the option of invisible indexes. What are invisible indexes? An invisible index can’t be ‘seen’ by any session by default, so it can be created and remain unavailable until testing is scheduled. This can be confusing since (more...)
Sometimes statements take longer than you’d like to complete. This can happen for a number of reasons including data changes, table growth, stale statistics and the occasional optimizer bug you haven’t encountered before. When it’s a SQL query that is misbehaving it’s pretty easy to find the cause and, in many cases, fix it. When it’s PL/SQL it isn’t as easy to do. There are views available from Oracle to assist in this endeavor and, (more...)
At March I will be presenting my very successful seminar “Mastering Backup and Recovery” in some countries of Latin America for the very first time. Thank you Panama, Chile and Brazil OUGs for inviting me to your amazing countries! Please, use the following links for registration and also to find more information about the seminar: […]
Hi All, On February 4, 2014 at 9:30 am PT I will be talking on the next OTN Virtual Developer Day about Oracle VM and Oracle Database. Come and discover the answers for the following questions: Does an Oracle Database perform well on a virtualized environment? What virtualization technology is more stable and […]
Some time ago, I received the request to migrate some Windows 2008 Servers to my Oracle VM farm and after complete the P2V migration the newly create VM would not start. It would crash on boot with blue screen and error: STOP: 0x0000007B (0xXXXXXXXX,0xXXXXXXXX,0×00000000,0×00000000) This issue is related to the storage drivers needed for the guest […]
I hit the following problem with a 188.8.131.52 database running on Windows 2003 this morning (info pulled from the alert log). The database had failed to restart after a client’s cold backup process ALTER DATABASE MOUNT Wed Jan 15 22:32:08 2014 ORA-09341: scumnt: unable to mount database OSD-04400: unable to acquire internal semaphore for process
I’ve been trying to install open source software. In this case an application called Moodle. I followed the instructions to install it on an Ubuntu Server vm but they were missing a couple of key points.
After installing the Moodle package (under “Moodle Installation” in the instructions) you need to (more...)
Top 5 Key Reasons Why Oracle VM is Best for Oracle Database When: Tuesday December 17th , 10am PST Register Here: http://event.on24.com/r.htm?e=725350&s=1&k=1512E332202610FE9518AB8B01354C6A&partnerref=Francisco Oracle VM application-driven architecture is designed for rapid deployment and ease of lifecycle management providing IT a highly scalable and cost effective virtualization solution for Oracle (more...)