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  • Concurrent statistics gathering in 12.1.0.2

    Prompted by an actual task at hand I spent some time investigating an 11.2.0.2 feature – concurrent statistics gathering. It has been on my to-do list for quite some time but so far I didn’t have a use case, and use cases make it so much easier. The question was-how can I gather statistics on a…

  • Little things worth knowing: ORACLE_SID, instance_name and the database names in Clusterware

    If you ever wanted to know how Clusterware works with registered database resources, read on! It takes a little while to get your head around the concepts of the ORACLE_SID, the instance_name and the database name as well. And how Clusterware deals with all of them. Although this post has been written on 12.1.0.2.0 on…

  • Interesting observations executing SLOB2 with ext4 and xfs on SSD

    My lab server has 2 SSDs, one is connected using SATA 2 and another is connected using SATA 3. I’d expect the SATA 3 connected device to be equally well equipped or even better to do work than the “old” interface. I ran SLOB on these devices to find out if there was a difference.…

  • Exadata and Virtual Private Database: will it offload my query?

    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 11.2.0.4. Since I’m a great fan of the Tom…

  • Little things worth knowing-troubleshooting parallel statement queueing

    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…

  • Interesting observation about standby redo logs in Data Guard

    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 12.1.0.2 on virtualised Linux, repeated on a proper platform with physical hardware. UPDATE: This is…

  • Can you have high redundancy files in a normal redundancy diskgroup?

    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,…

  • 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…