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April 2017

SQLcl on Bash on Ubuntu on Windows

I’m running my laptop on Windows, which may sound weird, but Linux is unfortunately not an option when you exchange Microsoft Word documents, manage your e-mails and calendar with Outlook and present with Powerpoint using dual screen (I want to share on the beamer only the slides or demo screen, not my whole desktop). However, I have 3 ways to enjoy GNU/Linux: Cygwin to operate on my laptop, VirtualBox to run Linux hosts, and Cloud services when free trials are available.

Now that Windows 10 has a Linux subsystem, I’ll try it to see if I still need Cygwin.
In a summary, I’ll still use Cygwin, but may prefer this Linux subsystem to run SQLcl, the SQL Developer command line, from my laptop.

SQL Monitoring, Flamegraph and Execution Plan Temperature 2.0

Two of the things that I like the most about SQL Monitoring reports are the ability to quickly spot where in the execution plan the time is spent (Activity% column, thank you ASH) and the fact you can collapse part of the plan. Too bad the two don’t “work” together meaning if you collapse a part of the plan the Activity% is not rolled up at the collapsed level. I understand why it works that way (it might be confusing otherwise) but I’d still like to be able to collapsed a node and get a “subtree Activity%” so I know if that subtree is something I should be worry about or not (kind of…).

Character selectivity

A recent OTN posting asked how the optimizer dealt with “like” predicates for character types quoting the DDL and a query that I had published some time ago in a presentation I had done with Kyle Hailey. I thought that I had already given a detailed answer somewhere on my blog (or even in the presentation) but found that I couldn’t track down the necessary working, so here’s a repeat of the question and a full explanation of the working.

The query is very simple, and the optimizer’s arithmetic takes an “obvious” strategy in the arithmetic. Here’s the sample query, with the equiavalent query that we can use to do the calculation:

Sharing a tablespace between 2 databases

I was reading an interesting discussion today about multiple databases each containing large amounts of read-only data.  If that read-only data is common, then it would make sense to have a single copy of that data and have both databases share it.

Well, as long as you can isolate that data into its own tablespace, then you can do that easily with Oracle by transporting the metadata between two databases and leaving the files in place.

Here’s an example

Source database

Conference Networking- Tips to Doing it Right

I was in a COE, (Center of Excellence) meeting yesterday and someone asked me, “Kellyn, is your blog correct?  Are you really speaking at a Blockchain event??”  Yeah, I’m all over the technical map these days and you know what?


I recently switched to a Mac after decades use with PCs.  I loved my Surface Pro 4 and still do, but that I was providing content for those I thought would be on Macs, it seemed like a good idea at the time.

New Online Oracle Security PUBLIC Training Dates Including USA Time Zones

We have just agreed three new online classes to be taught in June and July. These are for my two day class How to perform a security audit of an Oracle database. The classes are two day events and will....[Read More]

Posted by Pete On 12/04/17 At 02:17 PM

SUM is better than DISTINCT

There is a good chance that (based on this blog post title) that you’re expecting a post on SQL, and that’s understandable. But I’ll come clean nice and early – that was just to lure you in Smile

The post is about SUM and DISTINCT, but not in the technical sense.

Oracle IOTs against SQL Server Clustered Indexes

I’m itching to dig more into the SQL Server 2016 optimizer enhancements, but I’m going to complete my comparison of indices between the two platforms before I get myself into further trouble with my favorite area of database technology. In The Top 60 Oracle Database Blogs

I got a couple of emails over the last couple of weeks from Anuj at FeedSpot to tell me that my blog (This Oracle Security blog) has been listed in the top 60 Oracle Database blogs on the Feedspot website....[Read More]

Posted by Pete On 11/04/17 At 09:37 AM