First up was Joel with a session called, “Oracle Storage Fragmentation”, where he discussed the potential fragmentation issues possible in tablespaces, tables and indexes. If you’ve been a DBA for a long time it’s easy to think everyone knows this stuff, but I get asked questions about this stuff a lot! The session had a good mix of content, with something to (more...)
The Data Guard Broker is recommended for various reasons, this one is less obvious: It prevents a Split-Brain problem that may otherwise occur in certain situations. Let me show you:
[oracle@uhesse ~]$ dgmgrl sys/oracle@prima DGMGRL for Linux: Version 188.8.131.52.0 - 64bit Production Copyright (c) 2000, 2013, Oracle. All rights reserved. Welcome to DGMGRL, type "help" for information. Connected as SYSDBA. DGMGRL> show configuration; Configuration - myconf Protection Mode: MaxAvailability Members: prima (more...)
“Tuned” in RHEL7/OEL7 is tuning daemon for automatically tuning the system via the use of tuning profile. It can also be configured to react to changes to improve performance of the server and also to make system settings persistent.
“tuned-adm” is a command line tool that provides a number of different profiles to improve performance.
Below are the profiles provided and supported in RHEL 7 :-
Apart from the (more...)
Recently I have been asked how the Copy-on-Write cloning works on the ZFS Storage Appliance. More specifically, the question was about the “master” copy: did it have to be static or could it be rolled forward? What better than a test to work out how it works. Unfortunately I don’t have an actual system available to me at home so I had to revert to the simulator, hoping that it represents the real appliance accurately.
With the addition of the Configuration Management from OpsCenter to Enterprise Manager 13c, there are some additional features to ease the management of changes and drift in Enterprise Manager, but I’m going to take these posts in baby steps, as the feature can be a little daunting. We want to make sure that you understand this well, so we’ll start with the configuration searches and search history first.
“REDO_TRANSPORT_USER” was an Oracle Database Parameter that was introduced in Oracle release 11.1 to help transporting redo from a primary to a standby by using a user designated for log transport , The default configuration assumes the user “SYS” is performing the transport.
This distinction is very important since the user “SYS” is available on every Oracle database and as such most data guard environment when created with default settings are created with “SYS” (more...)
Oracle cost-based optimizer (CBO) is great, but sometimes it’s making wrong choices even when correct inputs are fed to it. In such cases, you need a tool to override CBOs choices, and one of the most popular tools is optimizer hints. The main reason they’re so popular is that they allow “quick-and-dirty” kind of fixes for performance issues (provided that query text can be altered). Other ways may be more reliable, but generally require more (more...)
This isn’t directly Oracle related but it did come to light within an Oracle context
We had a problem with a password file in a RAC cluster and whilst they appeared to be the same on both nodes of a cluster there were issues. I knew we needed to check the size of the files and ensure they were the same but I could not remember the (l)Unix command.
I knew it was to do (more...)
To build Oracle Clusterware Database at Home, I believe , RAC ATTACK is the best place to learn. Its is a free curriculum and platform for hands-on learning labs related to Oracle RAC. While reviewing the article, I thought to perform 12cR1 RAC installation on OEL 7.2.
Attached is the document :- 12c_RAC_on_OEL7
The attached article is inspired by
Deploying Oracle RAC (more...)
It’s time to announce the 3rd episode of Gluent New World webinar series! This time Gwen Shapira will talk about Kafka as a key data infrastructure component of a modern enterprise. And I will ask questions from a old database guy’s viewpoint :)
Apache Kafka and Real Time Stream Processing
I wanted to go to Hotsos Symposium for quite some time, having heard so many great topics from there for years. And every time I was a bit lazy to think about what I can talk about. Apparently I thought that everything I know is well covered elsewhere, so why would I be accepted. Plus all these complexities of budget, getting a visa, travel arrangements, jet lag, and personal matters in between. Last year, when (more...)
Here’s a possible bug (though maybe “not a bug”) that came up over the weekend on the OTN database forum. An application generating lots of “literal string” SQL was tested with cursor_sharing set to force. This successfully forced the use of bind variable substitution, but a particular type of simple insert statement started generating very large numbers of child cursors – introducing a lot of mutex waits and library cache contention. Here’s a (substituted) statement (more...)
Security asked to determine when certain passwords were last changed and I used the ptime column in user$ table to find out.
set lines 120 set pages 60 col name form a30 col Last_Changed form a12 SELECT name,ptime "Last_Changed" FROM sys.user$ a, dba_users b where a.name=b.username order by 1;
NAME Last_Changed ------------------------------ ------------ ANONYMOUS 24-AUG-13 APEX_030200 24-AUG-13 APEX_PUBLIC_USER 24-AUG-13 APPQOSSYS 24-AUG-13 CTXSYS 24-AUG-13 DBSNMP 13-MAY-16** DIP 24-AUG-13 EXFSYS (more...)
I have been applying PSU lately and what’s so hard out it?
Four+ databases running on Primary with DG Broker for standby.
There are no conventions, as some standby databases have dr appended to primary name while others have 2 appended to primary name.
I wanted to view the DG configuration for currently active instances and show_dg_config.sh will show me this.
Next, I want a faster way to shutdown DG by having syntax generated (more...)
Prompted by comments made by readers about my posts describing how to add a second SCAN in 12c Release 1 and problems regarding the listener_networks parameter I thought it was time to revisit the situation. I’m still running Oracle Linux 7.1/UEK3 (although that should not matter) but upgraded to 184.108.40.206.5. This is the release that is reportedly showing the odd behaviour. I don’t recall my exact version when I wrote (more...)
Today’s video is a sprint through some of the JSON support in Oracle Database 12c.
If videos aren’t your thing, you might want to read these instead.
- JSON Support in Oracle Database 12c Release 1 (220.127.116.11)
- Indexing JSON Data in Oracle Database 12c Release 1 (18.104.22.168)
- APEX_JSON Package: Generate and Parse JSON Documents in Oracle
Followers of the blog will know I’ve recently migrated the website to AWS. Yesterday I bit the bullet and cancelled my dedicated server.
As part of that process I had to move my email account from that service too. I always pull all my emails into Gmail, so there is no point paying for something cool. A little POP account is fine.
I started the process yesterday afternoon/evening, thinking it would be a quick drop on (more...)