This is interesting. I have always thought oracle latches were kind of mysterious, for lack of a technical term. Don’t get me wrong, I understand semaphores (I have programmed with these before), and “test and set” operations on certain types…
Category: Database
sudo and LD_LIBRARY_PATH … never the twain shall meet
While writing something for our operations support team to use when running a particular process, I found that sudo does not recognize a previously exported value for LD_LIBRARY_PATH. It also won’t use what is in the .bashrc or .profile for…
JDBC connection timeout
While testing a remote data center today, we had some network connectivity issues. We twiddled our thumbs while waiting for connections to throw an exception due to a network block. I found the setLoginTimeout() method on the DriverManager class. You…
How long will my flashback database command take?!!
Oracle 10g introduced the wonderful (and I mean wonderful) ability to “rewind” a database back to a point in time, rather than restoring a backup and rolling it forward in time using transaction logs. This technology is called flashback database,…
How close am I to realtime with dataguard and maximum performance (asynchronous) mode?
Oracle supplies two views to monitor how up to date your standby database is when compared to your primary database. One view is v$dataguard_stats, and the other is v$standby_apply_snapshot. Each of these views is only updated every 30 seconds, or…
Manually subscribing to Oracle FAN events
JDBC and dot Net clients are the recommended way to automatically subscribe to high availability events in an Oracle clustered environment, AKA, a RAC. I was curious as to how this could be implemented using your own code behind the…
Can’t add a service already registered with the listener
This morning, while testing on a two node 10.2.0.3 EE SLES 10 cluster, I found that using srvctl to remove a service from the clusterware does not necessarily stop the service and de-register it from the listener. I’m not sure…
At least one case where rebuilding indexes helps…
We found that after deleting 250 million “lower” rows from a table with a monotonically increasing sequence, our MIN range scans were incredibly slow. Richard Foote describes this much more clearly than I can this morning, so all this post…
Custom repeat_interval for dbms_scheduler
Nothing fancy today, just a simple test case regarding the subject line 🙂 create or replace function mytime return date as begin return sysdate + 5 / 1440; end; / create table foo (c date); create or replace procedure test_interval…
Poor man’s parallel DML
We were recently required to get rid of 250 million rows in a partitioned audit table. While the table is partitioned, we have global indexes that would be rendered unusable after dropping or truncating a partition. The UPDATE GLOBAL INDEXES…