During one of the classes I taught about Exadata optimisations I had an interesting question:
If I am using VPD, will Exadata still offload the query?
Background is that we discussed function offloading, and the meta-view v$sqlfn_metadata. It turned out that SYS_CONTEXT() is not offloadable in 126.96.36.199.
SQL> select name,datatype,analytic,aggregate,offloadable,descr
2 from v$sqlfn_metadata where name = 'SYS_CONTEXT';
NAME DATATYPE ANA AGG OFF DESCR
-------------------------------------------------- -------- --- --- --- ------------------------------
SYS_CONTEXT UNKNOWN NO (more...)
This is yet another one of these posts that hopefully help you as much as they are going to help me in the future. Recently I enjoyed troubleshooting a problem related to parallel execution. Since I have never really written down how to tackle such a problem I thought it might be nice to do that now.
This is 188.8.131.52.0 on Exadata, but the platform doesn’t really matter for the troubleshooting (more...)
Some of you might have followed the discussion around the number of standby redo logs on twitter, but since 140 characters are woefully short for the complete story here’s the writeup that prompted the question. This is a test with 184.108.40.206 on virtualised Linux, repeated on a proper platform with physical hardware.
First of all here’s my setup. I have a dbca-based database (CDB, but doesn’t matter) that features 3 groups for (more...)
One of the perks of teaching classes is that I get to research questions asked. In the last Exadata Administration Class I taught someone asked: can you have your disk groups in Exadata on normal redundancy yet have certain databases use high redundancy? This would be a good interview question …
The answer is yes, which I remembered from researching material on the 11g RAC book but I wanted to prove that it is the (more...)
I have been teaching the Enkitec Exadata Administration Class this week and made an interesting observation I thought was worth sharing with regards to IO Resource Management on Exadata.
I have created a Database Resource Manager (DBRM) Plan that specifically puts a resource consumer group to a disadvantage. Actually, quite severely so but the following shouldn’t be a realistic example in the first place: I wanted to prove a point. Hang-on I hear you say: you (more...)
I didn’t intend to write another blog post yesterday evening at all, but found something that was worth sharing and got me excited… And when I started writing I intended it to be a short post, too.
If you have been digging around Oracle session performance counters a little you undoubtedly noticed how their number has increased with every release, and even with every patch set. Unfortunately I don’t have a 11.1 system (or (more...)
I have recently upgraded my RAC 220.127.116.11.3 system to RAC 18.104.22.168 including the RDBMS installation. Currently I am updating my skills with information relevant to what I would normally have called 12c Release 2 (so that would also answer the question: when is 12c Release 2 coming out?). Then I realised I haven’t posted a first look at RAC 12c post yet-so here it comes.
There are (more...)
This is probably as much a note-to-self as it can possibly be. Recently I have enjoyed some more in-depth research about how the Linux kernel works. To that extent I started fairly low-level. Theoretically speaking, you need to understand the hardware-software interface first before you can understand the upper levels. But in practice you get by with less knowledge. But if you are truly interested in how computers work you might want to consider reading (more...)
Oracle 22.214.171.124 is out, after lots of announcements the product has finally been released. I had just extended my 126.96.36.199.3 cluster to 3 nodes and was about to apply the July PSU when I saw the news. So why not try and upgrade to the brand new thing?
What struck me at first was the list of new features … Oracle’s patching strategy has really changed over time. I (more...)
I had an interesting discussion as part of my latest presentation at the UKOUG RAC CIA & Database Combined SIG. Part of my talk was about the implications of the new threaded execution model in Oracle.
Since “we do not use Windows” (except for gaming) I can’t compare the Windows thread model to the new 12c implementation on UNIX. There are however interesting implications when switching to the new model, some of which I’d like (more...)