Tuning the locks of SGA

This post describes some deep knowledge of SGA.

LOCK_SGA is used to make sure that the contents from the SGA are not flushed, i.e data from the DB buffer cache not written back to disc. It is like to pin the contents of SGA.

SGA_LOCK  locks the entire SGA into physical memory. It is usually advisable to lock the SGA into real (physical) memory, especially if the use of virtual memory would include storing some of (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...)

Relationship between MEMORY_TARGET, SGA_TARGET and PGA_AGGREGATE_TARGET

Today’s article is about to add some deep knowledge in the Oracle’s database knowledge. We are going to have look at basic elements of Oracle database. This article is most useful for freshers and beneficial for experienced DBAs too.

In Oracle Database we read about MEMORY_TARGET, SGA_TARGET, and PGA_AGGREGATE_TRAGET. Let’s have a technical definition of these teams.

MEMORY_TARGET:- It is a database initialization parameter (introduced in Oracle 11g) that can be used for automatic PGA (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...)

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...)

Oracleasm Utility For ASMLIB

In this article, we are going to have look on Oracleasm Utility For ASMLIB.These lines explain the technical definition of Oracleasm The oracleasm command utility is part of the Oracle ASMLib, and you only use oracleasm commands when you want Oracle ASMLib to be able to access your ASM disks.

Oracle notes that the ASMLib is an optional support library for the Automatic Storage Management feature of ASM.  They claim that ASMLib simplifies (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...)

Steps for Create Standby Database From OEM 13c Cloud Control

In this post, we are going t have look on steps creation of Standby Database From OEM 13c Cloud Control.Creating or adding standby database for an existing primary database is a matter of few clicks in OEM 13c cloud control.

Prerequisites:

1. Source database is already registered in cloud control.

2. An agent is deployed target host.

3. Oracle binary is installed on target host ( same version and patchset of source DB).

STEPS:

 1. Go to (more...)

Why being wrong can be awesome

OK, Now that I’ve started the post with a nice click-bait heading, let’s get down to the business of being wrong. Smile

I did a lot of conference presentations last year, and the great thing about that for me was that I got to meet a lot of new people in the Oracle community in the Developer and DBA space. One of the questions that came up over and over again was about putting one’s knowledge (more...)

Linux for the SQL Server DBA- Part II

So we’ve covered a few basics of a Linux host in Part I

  • The File System
  • Users, groups
  • Basic Commands with basic arguments
  • And file and directory permissions

Hopefully, what I share next will build on the first post and enhance your knowledge as you move forward with Linux.

Reading the contents of a directory, gathering information on files and locating files are some of the most common tasks a DBA will perform as (more...)

Python sortedcontainers has me thinking

I was looking at the Python sortedcontainers package and it got me thinking. It is a long convoluted story and I am not sure that I can explain it clearly in a short blog post. I tried to explain all this to my wife in the last few minutes as we were driving up to a friend’s house last night and I’m sure it was confusing the way I explained it. But, I’m hoping that (more...)

Question Time

It’s that time of year again – the UKOUG Tech conference is approaching and I’ve organised a panel session on the Cost Based Optimizer.

This year I’ve got Christian Antognini, Nigel Bayliss, Maria Colgan and special guest star, all the way from Australia, Richard Foote on the panel, with Neil Chandler and Martin Widlake taking on their inimitable role of MCs.

If you’ve got any questions you’d like to put to the panel, you will (more...)

Drop a Oracle RAC Database

I am demonstrating how we can drop the database in RAC environment manually in Oracle12c(12.1.0.2.0) version.

I have two node RAC and the database name is TEST.  The instance names are TEST1 & TEST2.

  1. Verify the instance

[oracle@host01 ~]$ srvctl status database -d TEST
Instance TEST1 is running on node host01
Instance TEST2 is running on node host02

[oracle@host01 ~]$ crsctl status resource -t
--------------------------------------------------------------------------------
Name Target State Server State  (more...)

Oracle Cloud (DBaaS): Migration “On-prem” database to Cloud Using RMAN Cross-Platform Transportable PDB

This article was written by Skant Gupta and Joel Perez in Oracle OTN.

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This method can be used only if the on-premises platform is little endian, and the database character sets of your on-premises database (more...)

How to expand Exadata Database Storage capacity on demand



Exadata Storage expansion

Most of us knew the capabilities that Exadata Database Machine delivers. Its known fact that Exadata comes in different fixed rack size capacity: 1/8 rack (2 db (more...)