In the very lengthy previous post about the MAA connect string I wanted to explain the use of the MAA connection string as promoted by Oracle. I deliberately kept the first part simple: both primary and standby cluster were up, and although the database was operating in the primary role on what I called standby cluster (again it’s probably not a good idea to include the intended role in the infrastructure names) there was no (more...)
Sorry for the long title!
I had a question during my session about “advanced RAC programming features” during the last Paris Oracle Meetup about the MAA connection string. I showed an example taken from the Appication Continuity White Paper (http://www.oracle.com/technetwork/database/options/clustering/application-continuity-wp-12c-1966213.pdf). Someone from the audience asked me if I had experienced any problems with it, such as very slow connection timeouts. I haven’t, but wanted to double-check anyway. This is a (more...)
I recently applied system patch 20132450 to my 184.108.40.206.0 installation on a 2 node RAC system on Oracle Linux 7.1. While ensuring that OPatch is the latest version available I came across an interesting command line option in opatchauto. It is called “-generateSteps”.
[oracle@rac12sby1 ~]$ $ORACLE_HOME/OPatch/opatchauto apply -help
OPatch Automation Tool
Copyright (c) 2015, Oracle Corporation. All rights reserved.
Apply a System Patch to Oracle Home. User specified the (more...)
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 Release 2 Concepts Guide, chapter 19 “Direct Path Insert”. Quoting from there:
During direct-path INSERT operations, Oracle appends (more...)
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 220.127.116.11/18.104.22.168.1 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 and HCC compressed for query high) and import it into a different user’s (more...)
I think I’ll create this as a sticky post as soon as I found out how this works in WordPress :) This is going to be a list of my public appearances in 2015.
Paris Oracle Meetup
The next time I’ll be speaking publicly is on April 15 in Paris at the Paris Oracle Meetup. Many thanks go to @Ycolin and @BertrandDrouvot for inviting me to my first ever presentation in France! I am very (more...)
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 to be done when reading them.
Catching up with now, and direct path reads. You probably noticed that the migration (more...)
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 using direct path reads and Smart Scans.
The article ultimately aims at describing the enhancements Exadata brings to the table (more...)
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 22.214.171.124.0 on Oracle Linux 6.6/UEK3 in a KVM in case anyone is interested. I/O times aren’t stellar on that environment. It’s Oracle Restart, (more...)
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:
SQL> select * from v$parameter_valid_values where name ='_serial_direct_read';
no rows selected
OK so if Oracle doesn’t tell me then maybe I can work it out? Getting the view_text has worked in the past:
SQL> select view_name, text_vc from dba_views where view_name like '%PARAMETER_VALID_VALUES'