Sometimes, advanced features can bring advanced problems. Seeing a project with hundreds of child cursors with a different execution plan each, is never a pleasure, but there has to be a reason. In fact, we are talking about the “USE_FEEDBACK_STATS” reason in v$sql_shared_cursor. Its meaning is: “A hard parse is forced so that the optimizer can reoptimize […]
Oracle: How to create a good execution plan
Sometimes you simple need to know whether a statement is fast or not, or why it is slow. (Sadly, it seems like virtually nobody wants to know why a statement is fast, but that’s another story…) Do not use EXPLAIN PLAN in such cases, it does not (can not) deal bind variables right. I’ve got […]
Oracle 11g Adaptive Cursor Sharing does not work with PL/SQL?
Recently, there was trouble in the air. I migrated a database into 11g to enjoy adaptive cursor sharing, but it did not adapt cursors. In the trouble shooting process, I discovered the following: Bug 8357294: ADAPTIVE CURSOR SHARING DOESN’T WORK FOR SQL FROM PL/SQL Nice one. A short quotation from the bug text: PL/SQL has […]
Oracle 11g: Password expired, account locked – unwanted!
Hi, it’s old news, but oracle 11g expires passwords after 180 days, and locks you out if you mistype your password 10 times, and most DBAs don’t like that. It’s unsecure, but for client-server-applications a locked account is no single-user-annoyance, it’s a downtime killing SLAs, nerves and – hopefully not – DBA jobs. So just […]
Oracle 11gR2 ASM / ACFS: A first benchmark (poorly)
Hi folks, since Oracle 11g Release 2 is out now, I had to test one of the most-missed ASM features: the ASM cluster file system ACFS. My Setup: Two VMware nodes with 2 CPUs and 1,5GB of RAM each Oracle Enterprise Linux 5.3 x86_64 Four virtual cluster disks from the ESX server, 10GB in size […]
Oracle 11gR2 ASM: Changed permission policy (ORA-15260)
Did you recently see the new error ‘ORA-15260: permission denied on ASM disk group’ in your ASM administration? Maybe you are still connected as SYSDBA, old habit from 10g? A quick citation from the Oracle Docs: The SYSOPER privilege permits the following subset of the ALTER DISKGROUP operations: diskgroup_availability, rebalance_diskgroup_clause, check_diskgroup_clause (without the REPAIR option). […]
Oracle 11g look-at’s
That’s a personal, quite unsorted list of (new or older) features I recently collected. All of them are things, I’d consider valuable or at least important to care about as soon as 11g is involved. It might be for system architecture knowledge, concept tasks, DBA hands-on, good-to-know or any other thing that my happen in […]