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  • Little things worth knowing: direct path inserts and referential integrity

    This is another post to remind myself that Oracle evolves, and what I thought I knew might no longer be relevant. So double-checking instead of assuming should become a habit! Today’s example: direct path inserts. I seemed to remember from Oracle 9i that a direct path insert ignores referential integrity. This is still confirmed in the 9i…

  • Little things worth knowing: exp/imp vs expdp and impdp for HCC in Exadata

    Do you know the difference between exp/imp and expdp/impdp when it comes to importing HCC compressed data in Exadata? If not, then follow me through two examples. This is on 11.2.0.3/11.2.3.3.1 but applies to all database releases you can have on Exadata. The task at hand is to export a table (which happens to be non-partitioned…

  • Understanding enhancements to block cleanouts in Exadata part 2

    In part 1 of the series I tried to explain (probably a bit too verbose when it came to session statistics) what the effect is of delayed block cleanout and buffered I/O. In the final example the “dirty” blocks on disk have been cleaned out in the buffer cache, greatly reducing the amount of work…

  • Understanding enhancements to block cleanouts in Exadata part 1

    Travel time is writing time and I have the perfect setting for a techie post. Actually I got quite excited about the subject causing the article to get a bit longer than initially anticipated. In this part you can read about block cleanouts when using buffered I/O. The next part will show how this works…

  • What happens in ASM if usable_file_mb is negative and you lose a failgroup

    Having read the excellent post “Demystifying ASM REQUIRED_MIRROR_FREE_MB and USABLE_FILE_MB” again by Harald von Breederode I wanted to see what happens if you create a setup where your usable_file_mb is negative and you actually have to rebalance after a fatal failgroup error. I am using 12.1.0.2.0 on Oracle Linux 6.6/UEK3 in a KVM in case anyone…

  • How to resolve the text behind v$views?

    This is a common problem I have and I never write it down (except now). For example, today I wanted to know what the valid parameters for _serial_direct_read were: OK so if Oracle doesn’t tell me then maybe I can work it out? Getting the view_text has worked in the past: I’m sure I did…

  • Adaptive plans and v$sql_plan and related views

    Adaptive plans are one of the coolest new optimiser features in Oracle 12c. If you haven’t seen or heard about them in detail I recommend the following resources: Kerry Osborne’s presentation about the feature (and a link to the recording) Tim Hall’s article about the same feature Link to adaptive plans in the official documentation…

  • Installing Oracle 12.1.0.2 RAC on Oracle Linux 7-part 2

    In the first part of the article series you could read how a kickstart file made the installation of Oracle Linux 7 a lot more bearable. In this part of the series it’s all about configuring the operating system. The installation of Grid Infrastructure and the Oracle database is for another set of posts. There…

  • Installing Oracle 12.1.0.2 RAC on Oracle Linux 7-part 1

    Now that 12.1.0.2 is certified on RedHat Linux 7 and spin-off environments it’s time to test the installation of RAC on such a system. The installation of the OS is different from Oracle Linux 5 and 6-with these distributions was very straight forward how to install the operating system the method has changed significantly in…

  • RAC One Node 12c-revisited on ODA 12.1.2.1.0 featuring database on ACFS

    Thanks to Andy Colvin (@acolvin) and the Enkitec lab I have been able to get my hands on an ODA X4-2. And since that’s a lot quieter than turning on my own lab server, and also a lot faster I used the environment to test RAC One Node in 12.1.0.2.1. I recently had a question…