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July 2013

12c: Intro To Multiple Indexes On Same Column List (Repetition)

From an indexing perspective, one of the bigger ticket items introduced with Oracle Database 12c is the new capability to create multiple indexes on the same column list. It’s even a feature listed in the New Features Guide This can be particularly useful when you want to change the index definition in some way but you […]

Dtrace probes in Oracle 12c… v$kernel_io_outlier is populated by dtrace!!

Oracle 12c certainly has some great features, but for the performance guy like myself, performance monitoring features are particularly interesting.  There are three new v$ tables that track anomalies in the IO path.  The idea is to provide more information about really poorly performing IO that lasts more than 500ms.

  • V$IO_OUTLIER : tracks the attributies of an IO.  The size, latency as well as ASM information is recorded.
  • V$LGWRIO_OUTLIER : tracks information specifically on Log writer IO.

These two tables are going to be useful to monitor when performance issues occur.  I can already see the SQL scripts to monitor this activity starting to pile up.  But, there is one little extra table that dives even further into the IO stack using Dtrace.

Dtrace probes in Oracle 12c… v$kernel_io_outlier is populated by dtrace!!

Oracle 12c certainly has some great features, but for the performance guy like myself, performance monitoring features are particularly interesting.  There are three new v$ tables that track anomalies in the IO path.  The idea is to provide more information about really poorly performing IO that lasts more than 500ms.

  • V$IO_OUTLIER : tracks the attributies of an IO.  The size, latency as well as ASM information is recorded.
  • V$LGWRIO_OUTLIER : tracks information specifically on Log writer IO.

These two tables are going to be useful to monitor when performance issues occur.  I can already see the SQL scripts to monitor this activity starting to pile up.  But, there is one little extra table that dives even further into the IO stack using Dtrace.

Scripts to Download Oracle Database 12c Release 1 Documentation

In the past (here and here) I already shared with you the scripts I used to download the documentation related to Oracle Database. The aim of this short post is to provide the scripts I just wrote for the latest version: 12c Release 1.

Happy download as well as happy reading!

PS: it is interesting to note that the number of manuals is more or less stable. Some were added (e.g. SQL Tuning Guide), some were removed (e.g. all related to OWB).

Unlock Your Data

 Data virtualization  takes a single data source, for example a set of data files, and allows multiple databases to share those data files as if each database has private sole access to those data files. The data files are kept coherent for each database by sharing the duplicate blocks while at the same time keeping modified blocks private to the database that made the change. Data virtualization for databases allows many copies of a database to share the majority of the underlying storage and allows copies to be provisioned in minutes for almost no storage overhead.

Data virtualization for databases accelerates enterprise application projects for businesses around the world by providing fast, flexible access to virtual data—dramatically lowering costs and complexity.

12c Determinism

Following a comment from Marcin Przepiorowski on my last post, it crossed my mind to check whether “with” functions can be deterministic – the answer seems to be “not yet”. Here’s a simple script that you can run from end to end to check current and future releases – it compares inline (with) and standalone functions when the “deterministic” keyword has been used.

Feeling raw about raw…

Its been well documented for a while that Oracle were not going to allow raw devices in 12….but this still seems brutal. 

8.1.12 Desupport for Raw Storage Devices

Starting with Oracle Database 12c, block file storage on raw devices is not supported. You must migrate any data files stored on raw devices to Oracle ASM, a cluster file system, or Network File System (NFS).This also affects the OCR and voting files for Oracle Clusterware. You cannot store the OCR or voting files on raw devices. Oracle Clusterware files must be moved to Oracle ASM before upgrading.

So for all those customers running raw (most typically seen on OS clusters, where clustered file systems were an additional license…) then you’ve got some more upgrades coming your way

Just in case I forget I’m an Oracle geek…

Here’s a little reminder…

work-friends

They are on my desk at work… :)

Cheers

Tim…