Multiplex Redolog In Oracle RAC

Being an Oracle DBA in the initial year of our we work on the standalone database. In the world of backup, we work on multiplexing of the redo log. But as in single instance database is different from RAC environment. Multiplexing means to keep multiple copies of redo log in different diskgroup. It is similar to that of multiplexing in standalone, Only change is RAC will have threads for the node.
i.e a 2 node (more...)

TWO_TASK Environment Variables Oracle 12c

There are two environment variables for Unix to connect an Oracle database.One of them is ORACLE_SID and the other one is TWO_TASK. ORACLE_SID is used for connecting a database which is installed to the same host. TWO_TASK is used for connecting an oracle database which is installed another host.

I must thank to my fellow DBA Pinto Das who provide this scenario and we both come out with below solution.

Database Details

CDB= orcl12c
PDB=  (more...)

Steps to add diskgroup in ASM

We know what is ASM in Oarcle . Today we have look on diskgroups. In this article we have discuseed about the technical defination on ASM  diskgroup in first two paragargh after that we have the steps which we use to add asm diskgroup
The main components of ASM are diskgroups, each of which comprises of several physical disks that are controlled as a single unit. The physical disks are known as ASM disks, while the (more...)

Finding EM Configuration

DIRECTORY STRUCTURE AND LOCATIONS OF IMPORTANT TRACE AND LOG FILES OF ENTERPRISE MANAGER CLOUD CONTROL 13C

MW_HOME=/u01/middleware
OMS_HOME=$MW_HOME/13.2.0
EM_INST_HOME=$OMS_HOME/gc_inst

ps -ef|grep agent_inst|tail -2
ps -ef|grep gc_inst|tail -2

OMS_HOME/install/setupinfo.txt
OMS_HOME/install/portlist.ini

 


OGG-00868/ORA-01291 – Missing log files with Integrated Extract

Oracle GoldenGate is reliant on the Oracle Redo Logs and Archive Logs when capturing transactions. Since I do a lot of testing on VMs (limited space) and in the cloud (limited space … don’t want to burn to much $), I often delete my archive logs. Normally this is not a problem; however, every once-in-awhile I delete more archivelogs than I should. This throws the IE into a state where it will not start because (more...)

Oracle 12.1 big table caching IO code path

Recently I was triggered about the ‘automatic big table caching’ feature introduced in Oracle version 12.1.0.2 with Roger Macnicol’s blogpost about Oracle database IO and caching or not caching (https://blogs.oracle.com/smartscan-deep-dive/when-bloggers-get-it-wrong-part-1 https://blogs.oracle.com/smartscan-deep-dive/when-bloggers-get-it-wrong-part-2). If you want to read something about the feature in general, search for the feature name, you’ll find several blogposts about it.

If you are not familiar with automatic big table caching, it’s a feature (more...)

Just installed Pivotal Cloud Foundry, what’s next should I login to Apps Manager?

I get this question often from customers. Pivotal Cloud Foundry has just been installed and the API endpoint to target the instance is working fine. In short we want to do the following before we get developers onto the platform to ensure we no longer using the UAA server admin login details from the CLI or Apps Manager UI.

  • Create a new ADMIN user which will be used to configure Apps Manager ORGS and spaces (more...)

Comparing queries…

How do you compare a rewritten query to its original version? Most of the time I just run a MINUS operation on the original and new query. Actually I execute two. Old query (A) MINUS New query (B) and vice versa (B) MINUS (A). Both should result in no rows. That way I thought I had proven that the resultsets for both queries are equal.
But there is a flaw in this assumption.

What if (more...)

Ubuntu 17.10: Upgrade from xorg to wayland: window decorations broken!

Today i upgraded my ubunto from 16.04 to 17.10:






Up to this step everything worked fine.
But after the reboot i got tiny window decorations. This had to do with some further changes to the unity desktop - i used compiz there and this broke the new wayland configuration.

I found some hints about
dpkg --purge compiz-plugins ...
but this did not really help.
The way out was this:
mv .compiz .compiz.old
(more...)

Beware of intensive slow query logging when using – log_queries_not_using_indexes

MySQL slow query log is great for identifying slow queries that are good candidates for optimisation. Slow query logging is disabled by default, but it is activated by DBA's or developers on most environments.

You can use slow query log to record all the traffic but be careful with this action as logging all traffic could be very I/O intensive and could have negative impact on general performance. It is recommended to record all traffic (more...)

Tuning by understanding your application



This is a short post to illustrate how the understanding of how an application works can make all the difference to how you an tune it. This is a real world case which is actually pretty simple but i think illustrates the point quite well.

The performance symptoms were as follows:

1) Live environment works fine
2) Copy of that environment is very slow performing a specifc function - the data between the two systems (more...)

nVision Performance Tuning: 2. Effects of Performance Options

This blog post is part of a series that discusses how to get optimal performance from PeopleSoft nVision reporting as used in General Ledger.

In this post, I examine the effect of different settings for the tree performance options on how the SQL is generated.  It is common, to see different performance options in use on different trees in the same SQL query.  It is important to be able to look at a piece of (more...)

Submitted two talks to Collaborate 18

I submitted my two talks to Collaborate 18 through IOUG. These are the same two that I submitted to RMOUG Training Days. Hopefully one of the talks will get accepted at one of the two conferences but I don’t know. The nice thing is that they are both professional development talks and a user group meeting might be more open to that sort of talk than a vendor (i.e. Oracle OpenWorld) conference. But, there (more...)

It’s From The Catalog


"Have you ever heard a blindfolded octopus unwrap a cellophane-covered bathtub?"
-- Norton Juster, The Phantom Tollbooth

Database upgrades aren’t terribly difficult in general, unless the upgrade is for an RMAN catalog database that has two catalogs with different versions. It’s completely ‘legal’ to have an 11.2.0.x RMAN catalog database with an additional 12.1.0.x catalog; this is where the going can get rough during an upgrade since the (more...)

Oracle Bundle Patches – release timing

I have to invest much of my time (at work) into Oracle and managing of patches, merge patches, patch requests and similar things.
At this task I identified an interesting (but probably worthless) information:
It seems a Bundle Patch (for Version 12.1) is defined approximately (at least) 40 days before it's released.
At least the 12.1.0.1.171017 BP follows this rule.

I have requested a lot of one-off and merge patches (more...)

Exadata Flash Cache enabled for Write Back

During Tests for an Migration of a major customer application we saw in our AWR reports that most of the jobs are very write intensive. This was the point where we would like to test what happens when we change the Flash Cache Mode from Write Through to Write Back.

What are the main benefits of Write Back mode:

  • it improves the write intensive operations while writing to flash cache is faster than writing to (more...)

VirtualBox 5.2.0 : My Problems (Solved)

VirtualBox 5.2.0 has recently been released, which you can read about here.

Downloads and changelog are in the usual places.

I decided to throw caution to the wind and install it on my Windows 7 PC at work. The installation went fine and an existing Oracle Linux 7.4 VM started and worked OK. When I tried to update the guest additions it failed to build, but the VM was still working without (more...)

Truncated CTAS statements seem to be no longer shortened

Many bloggers have already discussed that Oracle can truncate the text of a “create table as select” statement to 20 characters depending on your version and patch level. This can be a problem in case a CTAS statement is a resource hog, yet you don’t see the SQL text that is needed for troubleshooting. A quick search on My Oracle Support reveals this can happen on 11.2.0.4, 12.1.0.1 and (more...)

Friday Philosophy – Smart or Smart-Arse?

Many of you know what a “Smart-Arse” is. For those who do not…

A “Smart-arse” a person who is irritating because they behave as if they know everything or try to catch you out by misleading you.

A smart person will look at your problem and say something like “have you tried checking the array size?” and, 8 times out of 10, their input will help you solve your problem. It may not be (more...)

2017 SiOUG – Slovenia


Just as quickly as I had unpacked from #OOW17, it was time to think about the next 2 conferences. Slovenia and Croatia.

I spoke in Slovenia before in 2011. I was invited by Joze Senegacnik  who I knew from the Oak Table. I had had a wonderful time and we stayed in Portoroz on the coast. 

I didn't blog about that conference but I did comment on the three most wonderful user group presidents and (more...)