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Oracle Linux 8 (OL8) : Podman

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When Oracle Linux 8 (OL8) was released, one of the first things I did was check for the Oracle supplied Docker engine. Nothing.

Always free / always up tmux in the Oracle Cloud with KSplice updates

By Franck Pachot

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I used to have many VirtualBox VMs on my laptop. But now, most of my labs are in the Cloud. Easy access from everywhere.

GCP

There’s the Google Cloud free VM which is not limited in time (I still have the 11g XE I’ve created 2 years ago running there) being able to use 40% of CPU with 2GB of RAM:

20c: AWR now stores explain plan predicates

By Franck Pachot

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In a previous post https://blog.dbi-services.com/awr-dont-store-explain-plan-predicates/ I explained this limitation in gathering filter and access predicates by Statspack and then AWR because of old bugs about reverse parsing of predicates. Oracle listens to its customers through support (enhancement requests), though the community (votes on database ideas), and through the product managers who participate in User Groups and ACE program. And here it is: in 20c the predicates are collected by AWS and visible with DBMS_XPLAN and AWRSQRPT reports.

I’ll test with a very simple query on the 20c preview available in the Oracle Cloud DBaaS:

Oracle Linux 8 (OL8) : Vagrant and Docker builds for 19c Database

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A couple of days ago I mentioned the certification of Oracle database 19c on Oracle Linux 8 (OL8) with UEK6.

I’ve had a bunch of OL8 articles and builds for a while, but up until now they’ve included warnings to say they weren’t certified. Over the last couple of evenings I’ve made some changes, so I thought I would summarise then here.

from$_subquery$_NNN

This is a reference note for a question that came up as a comment on a lengthy note I wrote about reading execution plans.

How do you interpret something like: from$_subquery$_001@SEL$1 in the Query Block Name / Object Alias section of an execution plan.

The simple answer is that if you’ve got an inline view in the FROM clause of a query and you haven’t given the inline view an alias the optimizer will have to invent one – and this is what they look like.

As a quick demo here’s a script to create a couple of tables and then run a query that joins two inline views (using “ANSI”-style SQL), with variations on which of the inline views are named:

Oracle Linux 8 (OL8) : Updates – UEK6, Podman, Database 19c Certification

Last week I had a quick email exchange with Simon Coter from Oracle about a few things related to Oracle Linux 8. I’ve been a little out of the loop over the last few weeks because of some important world event or another, so I had a bit of catching up to do.

UEK6 Went GA

UEK6 had been in preview for a while. In March it went GA, and I managed to miss that until recently. Even if you don’t care directly about the Linux kernel, this was a big thing because it was the first UEK release on Oracle Linux 8, and most of us outside Oracle were thinking this would mark the start of certification of Oracle products on OL8 (see below).

The myth of NoSQL (vs. RDBMS) agility: adding attributes

By Franck Pachot

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There are good reasons for NoSQL and semi-structured databases. And there are also many mistakes and myths. If people move from RDBMS to NoSQL because of wrong reasons, they will have a bad experience and this finally deserves NoSQL reputation. Those myths were settled by some database newbies who didn’t learn SQL and relational databases. And, rather than learning the basics of data modeling, and capabilities of SQL for data sets processing, they thought they had invented the next generation of persistence… when they actually came back to what was there before the invention of RDBMS: a hierarchical semi-structured data model. And now encountering the same problem that the relational database solved 40 years ago. This blog post is about one of those myths.

Video : SQLcl : Format Query Results

In today’s video we demonstrate how to format query results in SQLcl using query comments and the SQLFORMAT setting.

For those of you that prefer to read, the video is based on this article.

The star of today’s video is Charles Wilson, who I got chatting with at the OTN lounge at a previous OpenWorld. </p />
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Execution Plans

In previous articles on reading execution plans I’ve made the point that the optimizer is very “keen” to transform complex queries into queries consisting of a single query block and that there’s a simple “First Child First (FCF)” rule for reading the plan for a single query block. I’ve then pointed out that when the optimizer can’t transform your query into a single query block you can still apply FCF to each “final” query block (outline_leaf) in turn, but you then have to work out how Oracle is connecting those query blocks and FCF is not guaranteed to apply between query blocks.