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Oracle ACFS: “du” vs. “df” and “acfsutil info”

By Franck Pachot

This is a demo about Oracle ACFS snapshots, and how to understand the used and free space, as displayed by “df”, when there are modifications in the base parent or the snapshot children. The important concept to understand is that, when you take a snapshot, any modification to the child or parent will

20 Years of

It was twenty years ago today that the first incarnation of my website was born.

It started life as a few scripts and notes put on the internet so I didn’t have to carry them around on floppy disks or CDs when I was moving around between contracts. I had been working with Oracle technologies for five years before the website was born, but most of the early content was Oracle 8i stuff.

Oracle Autonomous Linux: cron’d ksplice and yum updates

By Franck Pachot

Oracle Enterprise Linux (OEL) is a Linux distribution which is binary compatible with Red Hat Enterprise Linux (RHEL). However, unlike RHEL, OEL is open source, free to download, free to use, free to distribute, free to update and gets free bug fixes. And there are more frequent updates in OEL than in CentOS, the free base of RHEL. You can pay a subscription for additional support and features (like Ksplice or Dtrace) in OEL. It can run the same kernel as RHEL but also provides, still for free, the ‘unbreakable kernel’ (UEK) which is still compatible with RHEL but enhanced with optimizations, recommended especially when running Oracle products.

Most Recent – 2

A question arrived in my email a few days ago with the following observations on a statement that was supposed to query the data dictionary for some information about a specified composite partitioned table. The query was wrapped in a little PL/SQL, similar to the following:

Video : Hybrid Partitioned Tables in Oracle Database 19c

In today’s video we’ll give a quick demonstration of Hybrid Partitioned Tables, introduced in Oracle Database 19c.

The video is based on this 19c article.

The video only has a single example using external partitions pointing to CSV data. The article also includes and example using a Data Pump file.

The Oracle ACE program ♠ what it is not ♠

By Franck Pachot

I had a few questions about the Oracle ACE program recently and I thought about putting some answers there. Of course, that’s only my point of view, there’s an official web page:

The program is flexible and open, with a large diversity of people, technologies, contributions, levels,… Then rather than explaining what it is, which would be limiting, I’ll rather tell you… what it is not.

Some myths about PostgreSQL vs. Oracle

By Franck Pachot

I originally wrote this as a comment on the following post that you may find on internet:
but my comment was not published (many links in it… I suppose it has been flagged as spam?) so I put it there.

You should never take any decision on what you read on the internet without verifying. It is totally valid to consider a move to Open Source databases, but doing it without good understanding is a risk for your migration project success.

Video : Liquibase : Deploying Oracle Application Express (APEX) Applications

Today’s video is a quick demonstration of deploying an Oracle Application Express (APEX) application using Liquibase.

The video is based on a new article of the same name, which covers the deployment of both APEX workspaces and APEX applications using Liquibase.

Here’s some other content you might find useful.

Lower Cost Ignored

This is an update on a post I wrote nearly 10 years ago describing how the optimizer could choose to ignore a lower cost indexed access path and use a higher cost index if the lower cost were based on guesswork. The original article article used (select {constant} from dual) as a way of supplying an “unpeekable bind” in a predicate, but that mechanism stopped working 11gR2, hence the update.

The upate also goes into a little more detail about event 38036 which can be used to modify this behaviour by defining a “cut-off” percentage where Oracle will switch back to using the lower cost path.

We start with the code to generate the data – including, in this case – a table that I can query to supply “hidden constants” to the optimizer: