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This is one of my “black hole” articles – I drafted it six months ago, but forgot to publish it.

Insider View of a Delphix VDB Rewind

I love questions-  They give me something to write about that I don’t have to come up with from my experience or challenges…:)

So in my last post, Paul asked:

Quantum Space

Here’s a not very serious note that makes a serious point.  I’ve got a small tablespace made up of 4 files, and here’s a little report I can run against the data dictionary for that tablespace:


select 'File space' What, nvl(sum(user_bytes)/1048576,0) MB from dba_data_files where tablespace_name = 'LOB_TEST'
union all
select 'Free space',      nvl(sum(bytes/1048576),0)         from dba_free_space where tablespace_name = 'LOB_TEST'
union all
select 'Extents',         nvl(sum(bytes/1048576),0)         from dba_extents    where tablespace_name = 'LOB_TEST'
union all
select 'Segments',        nvl(sum(bytes/1048576),0)         from dba_segments   where tablespace_name = 'LOB_TEST'
;

The name of the tablespace isn’t significant – it happens to be a tablespace I created to do some tests relating to space allocation with securefile LOBs, and it’s been hanging around ever since.

Announcing SLOB 2.4! Integrated Short Scans and Cloud (DBaaS) Support, and More.

This post is to announce the release of SLOB 2.4!

VERSION

SLOB 2.4.0. Release notes (PDF): Click Here.

WHERE TO GET THE BITS

As always, please visit the SLOB Resources page. Click Here.

What is in a transportable tablespace dumpfile?

On 31st of May in Düsseldorf, at DOAG Datenbank, I’ll talk about transportable tablespaces and pluggable databases. Both methods are transporting data physically, the difference is in the transport of the metadata, which can be more flexible when transported logically, as with TTS, but faster when transported physically with PDB. I have a lot of demos to show transportable tablespaces with RMAN, and the different cloning features available in 12cR2. If I have time I’ll show what is inside the dumpfile when using Data Pump to export the metadata. Here is the idea.

expdp transport_tablespaces

Here is how we export metadata with Data Pump for transportable tablespaces.

AWS Database Blog – Added To My Blog Roll

This is just a brief blog post to share that I’ve added the AWS Database Blog to my blogroll.  I recommend you do the same! Let’s follow what’s going on over there.

Some of my favorite categories under the AWS Database Blog are:

 

 

Readers: I do intend to eventually get proper credentials to make some posts on that blog. All in proper time and with proper training and clearance.

Aliases

Here’s a performance problem that came up on OTN recently. The following query (reformatted) takes “ages” to run – how do you address the problem:

SELECT
	COUNT(*) 
FROM
	smp_dbuser2.workflow_step_report
WHERE
	report_ID IN (
		SELECT	report_id
		FROM	smp_dbuser2.workflow_report
		WHERE	trunc(start_time) = '28-Apr-2017'
		AND	user_id = 'nbi_ssc'
	)
;


Various pieces of relevant information were supplied (the workflow_report table holds 1.4M rows the workflow_step_report table holds 740M rows and some indexes were described), but most significantly we were given the execution plan:

Delivering Migration Projects on Time

I did a couple great sessions yesterday for the awesome Dallas Oracle User Group, (DOUG.)  It was the first time I did my thought leadership piece on Making Sense of the Cloud and it was a great talk, with some incredible questions from the DOUG attendees!

Quiz Night

If this is the closing section of thetkprof output from the trace file of a single end-user session that has a performance problem, what’s the most obvious deduction you can make about the cause of the problem, and what sort of action would you take next ?

Listener and Virtual IP

When you configure a standby database, you want the application to transparently connect to the primary database, wherever it is. That’s the role of Transparent Application Failover, but this requires configuration on the client side. If you can’t configure TAF, you can use a virtual IP address. But then the question is how to configure the listener.ora to handle connections to this VIP.

Don’t worry, if you configured everything as recommended, with the hostname declared in /etc/hosts, and listener.ora referencing this host name, then you can simply ignore the VIP for your configuration. The reason is that when the host specified in the listener.ora resolves to the same IP address as the hostname of the server, then Oracle listener binds the port on all interfaces, and this includes the VIP.