New leafmisscount Option in Flex Cluster 12c

In the Oracle RAC previous version we have worked with the option “misscount” of crsctl, which applies for all the servers because there was only one kind of servers, but in the new version of Oracle (12c) we have a new kind of RAC configuration, the “Flex Cluster”. With Flex Cluster we have two kinds of servers “Hub nodes” and “Leaf Nodes”, the Hub Nodes have the same concept of the normal nodes in the previous versions, however (more...)

#DOAG2014 bits of info for DBAs

Just wanted to share some pieces of information from the recent DOAG annual conference that you may find interesting.

From Mike Dietrich’s presentation about Database Upgrade:

Mike Dietrich

Database Replay is extremely useful to predict after-upgrade performance on a test system,

especially we can record the production load on 10g even.

From Carsten Czarski’s talk about XML DB:

Carsten Czarski

With 12c, XML DB is mandatory and it provides an easy way to upload BLOBs via ftp into the (more...)

UKOUG and OU Team up at Annual Conference

The UK Oracle User Group (UKOUG) is hosting the Tech14 and Apps14 conferences jointly in Liverpool this year and I am proud to have been involved in organising the Oracle University Certification Exam  Test Fest.   User Group members attending the conference and who book in advance for one of the 120 available exam slots will get […]

Parallel Costs

While creating a POC of a SQL rewrite recently I received a little surprise as I switched my query from serial execution to parallel execution and saw the optimizer’s estimated cost increase dramatically. I’ll explain why in a moment, but it made me think it might be worth setting up a very simple demonstration of the anomaly. I created a table t1 by copying view all_source – which happened to give me a table with about 100,000 rows and 1117 (more...)

Why is “Dave Unknown” Trying to Social Media With Me?

I know some people share my opinion on this and others totally disagree – but I fail to appreciate why people I have never met, spoken with or care about want to Social Media with me. If we have not met but there is a high probability we share unusual interests then OK, perhaps – but the fact that we both can spell Oracle or know what a gene is does not count as unusual (more...)

Dumb… no module named dom during

ImportError: no module named dom This error suddenly appeared in two OAM environments, during startup of the stack, more specifically, weblogic startup ( The complete stack is: $DOMAIN_HOME/ CLASSPATH=/oracle/middleware/patch_wls1036/profiles/default/sys_manifest_classpath/weblogic_patch.jar:/oracle/middleware/jdk1.7.0_45/lib/tools.jar:/oracle/


APPEND hint in oracle is very useful, there are many benefits

Fragmented data loading – data will clustered above the HWM so that similar data will be together. Otherwise Oracle will place the records in blocks using PCT_FREE rule

  • No undo will be generated – in large direct path insert will free up large amount of data blocks
  • Less CBC latches (because of no UNDO blocks), less CPU usage
  • Readers need not undo the records, (more...)

OTN APAC 2014 : Auckland – Day 2

My day 2 at the conference started with my analytic functions session. I’m always a bit worried I oversimplify things, but people seem to appreciate it, so perhaps I’m just being paranoid. I’m sure the feedback will let me know. :)

Next I went to Chris Muir‘s session of Developing Web and Mobile Dashboards with Oracle ADF. I had already seen this at the AUSOUG WA event in Perth, but I liked it, so I (more...)

WordPress 4.0.1 Released

I got a bunch of emails this morning telling me by blogs had upgraded to WordPress 4.0.1. It’s a critical security release, so if you’ve not done an auto-update, you really need to get this sorted.

The downloads and changelog are in the usual places.



WordPress 4.0.1 Released was first posted on November 20, 2014 at 11:32 pm.
©2012 "The ORACLE-BASE Blog". Use of this feed is (more...)

Upgrading to – Dictionary View Performing Poor

Just a quick blog post on things you might see after upgrading to We recently upgraded database from to and query on some data dictionary views ran too slow.

1. Performace of query on dba_free_space degraded
2. Performance of query involving dba_segments is slow

DEV01> select ceil(sum(b.bytes)/1024/1024) b from sys.dba_free_space b;

Elapsed: 01:31:45.78

Searching MOS pointed to these Doc Ids (more...)

Conference Organisation from the Inside – UKOUG Tech14

An interesting experience I have had this year is being more involved in helping organise the annual UKOUG Oracle Technical Conference – Tech14 this year. I fully intended to blog about things as we progressed, but it never happened. But I thought it would be interesting to do a couple of blogs about it, for anyone interested,

If you have never helped organise a conference or user group meeting then you probably think there is (more...)

Quantum Data

That’s data that isn’t there until you look for it, sort of, from the optimizer’s perspective.

Here’s some code to create a sample data set:

create table t1
with generator as (
	select	--+ materialize
		rownum id
	from dual
	connect by
		level <= 1e4
	rownum					id,
	mod(rownum-1,200)			mod_200,
	mod(rownum-1,10000)			mod_10000,
	lpad(rownum,50)				padding
	generator	v1,
	generator	v2
	rownum <= 1e6

		ownname		 => user,
		tabname		 =>'T1',
		method_opt 	 =>  (more...)

Progress update on my AWR repository

I received an email from a team member yesterday

Have you seen this?

Interesting idea – ever thought of implementing it?

Well of course I have implemented a AWR data repository and I thought I would catch-up on where I am with it and how it is being used.

The database started out on HPUX on about 2 years ago and is now on Linux on 11. (more...)

OTN APAC 2014 – Auckland – Day 1

So it was really day 2 of the conference, but it was day 1 for me, so that’s the way I’m naming it… :) There were seven tracks available, but I’ll be speaking about what I saw…

First up was the keynote by Tim Ebbeck called 10 Rules of Transformational Leadership. I’m not the biggest fan of keynotes, but this one was pretty cool. To summarise:

  1. Nothing beats being as good as you can be. Get (more...)

OTN APAC 2014 : Auckland Day Off

The first day of the Auckland conference was made up of hands-on labs and workshops. I wasn’t presenting, so I arranged to meet up with some friends and have a play day. :)

On my way out of the hotel I saw Osama Mustafa, who is still looking buff like a Teenage Mutant Ninja Turtle. On the way to the station I met Anton Els, which was a pleasant surprise. We chatted for a (more...)

The Myth of Great Places to Work

Why do people have this crazy obsession of working for a specific company, or the perception that a company is great or not so great? People—especially those immediately around you—make up a huge part of the attractiveness of a company to work for; not companies themselves. Consider these factors first before you choose one to be a "dream" company.

It's not the traditional blog post I generally write. But it's something I consider near and (more...)


“You can’t compare apples with oranges.”

Oh, yes you can! The answer is 72,731,533,037,581,000,000,000,000,000,000,000.

SQL> create table fruit(v1 varchar2(30));
SQL> insert into fruit values('apples');
SQL> insert into fruit values('oranges');
SQL> commit;
SQL> begin
  2  	     dbms_stats.gather_table_stats(
  3  		     ownname	      => user,
  4  		     tabname	      =>'FRUIT',
  5  		     method_opt       => 'for all columns size 2'
  6  	     );
  7  end;
  8  /
SQL> select
  2  	     endpoint_number,
  3  	     endpoint_value,
  4  	     to_char(endpoint_value,'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx') hex_value
  5  from
  6  	      (more...)

Oracle Database 12C Certified Professional SQL Foundations by Steve Ries; Infinite Skills

How to become Become an Oracle Certified Associate? That's a good question for some people who want to start working on Oracle Database and get first Oracle Certification for their work life. Step 1 - Pass one SQL Exam: Oracle Database 12c: SQL Fundamentals 1Z0-061 or Oracle Database 11g: SQL Fundamentals I 1Z0-051 or Oracle Database SQL Expert 1Z0-047. Step 2 - Pass Exam Oracle Database 12c: Installation and Administration 1Z0-062.
With Step 1 -  Oracle (more...)

Change Parameter Value In Another Session

RSS content

The values of initialization parameters in another session can be changed  using procedures SET_BOOL_PARAM_IN_SESSION and SET_INT_PARAM_IN_SESSION provided in DBMS_SYSTEM package.

Let’s demonstrate:

SQL>conn / as sysdba

SYS> grant dba to hr;

– Currently parameter HASH_AREA_SIZE is set to 131073 in HR session

HR>> sho parameter hash_area_size

NAME                                 TYPE        VALUE
———————————— ———– ——————————
hash_area_size                       integer     131073

– Find out SID, SERIAL# for HR session

SYS> select sid, serial#, username from v$session where username=’HR’;

SID    (more...)

Oracle Virtual Technology Symposium: Download

For all those who attended my session today in Oracle Virtual Technology Summit on InMemory, thank you very much. Some questions were cut off towards the end since it was an automated session. I will be happy to answer, if your question was in that category.
Since this was an on-demand show, you can watch the replay anytime by visiting this site. Remember, this requires a connection to watch; it's not a download. You can  (more...)