12c

Do not set job_queue_processes at PDB level in 12.1.0.2

MOS Doc ID 2175443.1 goes into more detail, including the following quote: It is possible to set job_queue_processes at pdb level on 12.1.0.2 multitenant database, but it does not work correctly. I have managed to reproduce the actual behavior. Of particular concern is that this allows a local user on one PDB to disrupt things …

Do not set job_queue_processes at PDB level in 12.1.0.2 Read More »

Adaptive Dynamic Sampling and the Result Cache: RC Latch

After we migrated one of our instances from Oracle 11.2.0.4 to 12.1.0.2 we ran into some serious latch contention that basically took down the instance.  From online research, and discussion with other DBAs I don’t think we are the only customer that has run into this problem, so I wanted to share my investigation and …

Adaptive Dynamic Sampling and the Result Cache: RC Latch Read More »

Incorrect Cardinality Adjustment caused by Dynamic Statistics

During migration testing to Oracle 12, one of our teams complained about regression of a particular query. Drilling into what was going on identified some a problem with Adaptive Dynamic Sampling, and certainly not the first one we have encountered. I will detail the steps to reproduce, and my understanding of what is going on. …

Incorrect Cardinality Adjustment caused by Dynamic Statistics Read More »

“rtld: 0712-001 Symbol CreateIoCompletionPort was referenced” installing Oracle 12.1.0.2 on AIX

I first encountered this error message when installing 12.1.0.2 on AIX, and have since hit this with other Oracle software, particularly Enterprise Manager agent. HKE1DEV2@[/home/oracle]#sqlplus exec(): 0509-036 Cannot load program sqlplus because of the following errors: rtld: 0712-001 Symbol CreateIoCompletionPort was referenced from module /u01/app/oracle/product/12.1.0.2/client/lib/libttsh12.so(), but a runtime definition of the symbol was not found. …

“rtld: 0712-001 Symbol CreateIoCompletionPort was referenced” installing Oracle 12.1.0.2 on AIX Read More »