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  • Intra-Database IORM in action

    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…

  • A brief history of time^H^H Oracle session statistics

    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…

  • A first look at RAC 12c (part I)

    I have recently upgraded my RAC 12.1.0.1.3 system to RAC 12.1.0.2 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…

  • How to get insights into the Linux Kernel

    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…

  • Upgrading clustered Grid Infrastructure to 12.1.0.2 from 12.1.0.1.3

    Oracle 12.1.0.2 is out, after lots of announcements the product has finally been released. I had just extended my 12.1.0.1.3 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…

  • Implications of threaded_execution = true in 12c

    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…

  • Setting up Direct NFS on Oracle 12c

    Direct NFS is a great feature that I have finally had the time to investigate further. Since I always forget how to set it up and I didn’t find blog posts about this subject elsewhere I decided to put something together. In this configuration I am using a virtual machine named server1 to export a…

  • Why is P1 the only parameter populated in cell smart table scan?

    Anyone who has looked at Exadata might ask the question, and I did so too. After all, cell smart table scan is in wait class User IO so there should be more, right? This is what you find for a smart scan: Compare this to the traditional IO request: At first I didn’t understand as to why…

  • Why does the Optimiser not respect my qb_name() hint?

    I recently was involved in an investigation on a slow-running report on an Exadata system. This was rather interesting, the raw text file with the query was 33kb in size, and SQL Developer formatted the query to > 1000 lines. There were lots of interesting constructs in the query and the optimiser did its best…

  • My SDU goes to 11 ^h^h I meant 2097152

    One of the cool new things in 12.1 is that you can set the Session Data Unit to 2MB. This might not sound like a Big Deal, but getting this to work required me to dig deeper into the TNS layer than I intended…Then I somehow got stuck on the wrong track, thankfully the team…