Another question on a seemingly simple “not exists” query has appeared on OTN just a few days after my last post about the construct. There are two little differences between the actual form of the two queries that make it worth repeating the analysis.
The first query was of the form:
select from big_table
where not exists (select exact_matching_row from small table);
while the new query is of the form:
select from big_table alias1
This one is quick and short. I have been asked few time, how can we check what value was specified to OSDBA, OSOPER and OSASM,especially during upgrades (to know what was it set to which initial installation)
# The DBA_GROUP is the OS group which is to be granted OSDBA privileges.
# The OPER_GROUP is the OS group which is to be granted OSOPER privileges.
# The OSASM_GROUP is the OS group which is to (more...)
Vishal Desai systematically troubleshooted an interesting case where the initial symptoms of the problem showed a spike of enq: SQ – contention waits, but he dug deeper – and found the root cause to be quite different. He followed the blockers of waiting sessions manually to reach the root cause – and also used my @ash/ash_wait_chains.sql and @ash/event_hist.sql scripts to extract the same information more conveniently (note that he had modified the scripts to (more...)
I saw this database landscape 2014 overview from “451 Research” with an very nice visualization…
Oracle Midlands Event #9 is now confirmed with another great lineup!
Thanks to Red Stack Technology for sponsoring the event, allowing it to remain free!
Put the date in your diary. See you there!
Oracle Midlands : Event #9
was first posted on April 24, 2015 at 10:32 am.
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Overnight I got an auto-upgrade to WordPress 4.1.3 maintenance release and a notice telling me WordPress 4.2 “Powell” was released. The downloads are in the usual places, and of course available from the update screen in your blog.
The announcement page has a video explaining the new features, which seem to make it easier to repost other people’s content, where you would normally expect to just tweet a link. Not sure what (more...)
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...)
OK, time to reveal the solution to the somewhat tricky Singapore maths exam question I blogged previously. Remember, there were 10 dates: May 13 May 15 May 19 June 13 June 14 July 16 July 18 August 14 August 15 August 16 Bowie only knew the month of my birthday, Ziggy only knew the day. Bowie […]
I’ve just been motivated to resurrect a couple of articles I wrote for DBAZine about 12 years ago on the topic of bitmap indexes. All three links point to Word 97 documents which I posted on my old website in September 2003. Despite their age they’re still surprisingly good.
I’m trying to compare how a query runs on two different 184.108.40.206 systems. One runs on HP-UX Itanium and one runs on 64 bit x86 Linux. Same query, same plan, different hash value.
update seg$ set type#=:4,blocks=:5,extents=:6,minexts=:7,maxexts=:8,exts
ize=:9,extpct=:10,user#=:11,iniexts=:12,lists=decode(:13, 65535, NULL,
:13),groups=decode(:14, 65535, NULL, :14), cachehint=:15, hwmincr=:16,
spare1=DECODE(:17,0,NULL,:17),scanhint=:18, bitmapranges=:19 where
ts#=:1 and file#=:2 and block#=:3
Plan hash value: 1283625304
| Id | Operation | Name | Rows | Bytes (more...)
We are discussing the management of Oracle Database 12c in Oracle Enterprise Manager 12c. In our previous blog post on this topic, we looked at how the Self-Service console would appear to the Self-Service Application (SSA) user, with the ability to provision databases, schemas or PDBs on the fly.
Metering and Chargeback is an important feature of the cloud. Due to the agile self-service nature of the cloud, it is important to set up quotas (more...)
We are discussing the management of Oracle Database 12c in Oracle Enterprise Manager 12c. In our previous blog post on this topic, we looked at “Database as a Service” and “Schema-as-a-Service”, and also talked about “Pluggable database (PDB) as a Service (PDBaaS)”.
The “Schema as a Service” capability was introduced since the Cloud plug-in “Enterprise Manager for Oracle Cloud (SSA) 220.127.116.11”. The renamed plug-in “Oracle Cloud (more...)
We are discussing the management of Oracle Database 12c in Oracle Enterprise Manager 12c. In our previous blog post on this topic, we looked at the Database Resource Manager and how it can be used to control resources at the PDB level in Database 12c.
Let us now look at how Enterprise Manager’s “Database as a Service (DBaaS)” capability works with Database 12c and its container and pluggable databases.
Today I worked on silent upgrade of Oracle GoldenGate from 18.104.22.168.0 to 22.214.171.124.2, so thought to blog it which might help some of you. These are the steps I performed
Current GoldenGate Home –> /oracle/app/product/ogg12.1.2
1. Gather the details of GoldenGate Processes before stopping them
GGSCI> INFO EXTRACT EXTL, SHOWCH
INFO EXTRACT DPUMP, SHOWCH
GGSCI> SEND EXTRACT EXTL, SHOWTRANS
GGSCI> STOP EXTRACT DPUMP
GGSCI> STOP (more...)
Take a look at these two items from a form I was using today.
If, like me, you thought that checking those boxes meant you agreed with the statements, you would be wrong. It turns out what they mean is you’ve remembered to copy that text into the main body of your request. WTF?
I suggested to the company in question, they either make the check boxes work as they should, or at least change (more...)
WordPress 4.1.2 has been released. It’s a security release and I’m guessing most of you will pick it up passively using the auto-update features, so it’s nothing to worry about too much.
You can read about the fixes in this release here.
I’ve just installed it on 5 separate installations and there were no dramas.
was first posted on April 21, 2015 at 5:02 pm.
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I’ve been blogging now for almost 6 years and presenting at conferences for… 12 years (really? Good grief!). I’ve even written and delivered several courses, ranging from 1 day to 3 days in length. However, up until now I’ve never been what I would term published – ie managed to persuade another organisation or person to publish something I have written.
That changed a few days ago when the latest UKOUG “Oracle Scene” magazine (more...)
From time to time I read a question (or, worse, an answer) on OTN and wonder how someone could have managed to misunderstand some fundamental feature of Oracle – and then, as I keep telling people everyone should do – I re-read the manuals and realise that that sometimes the manuals make it really easy to come to the wrong conclusion.
Having nothing exciting to do on the plane to Bucharest today, I decided it (more...)
There’s a somewhat sour discussion going on based attached to the video at https://www.youtube.com/watch?v=jZW-uLb52xk
Whether you agree or disagree with the video or the comments, or (sadly) the animosity in them, it does lead to an interesting bit of investigation when it comes to data types with arbitrary precision, which was stumbled upon by a friend at work.
Let’s start with a simple comparison between two dates. In this case, I’ve just (more...)