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DBMS_CLOUD Package – A Reference Guide

The Appendix A of the Using Oracle Autonomous Data Warehouse Cloud guide describes the DBMS_CLOUD package. Unfortunately, it documents only a subset of the subroutines. And, for some of them, the description could also be enhanced. Therefore, while I was testing all the subroutines the DBMS_CLOUD package provides, I took a number of notes. By the end of my tests, I got what I can call my personal reference guide to the package. Since it might help others, here it is…

The APPROX_MEDIAN Function – A Test Case

The aim of this post is not to explain how the APPROX_MEDIAN function works (you find basic information in the documentation) but to show you the results of a test case I ran to assess how well it works.

Here’s what I did…

I started in the Oracle Database Public Cloud an instance of version 12.2.

Then I created a table with several numerical columns (the name of each column shows how many distinct values it contains), loaded 150 million rows into it (the size of the segment is 20 GB), and gathered the object statistics.

Oracle Database Cloud (DBaaS) Performance - Part 4 - Network

In the last part of this installment I'll have a brief look at the network performance measured in the Oracle DBaaS environment, in particular the network interface that gets used as private interconnect in case of RAC configuration. The network performance could also be relevant when evaluating how to transfer data to the cloud database.

I've used the freely available "iperf" tool to measure the network bandwidth and got the following results:

[root@test12102rac2 ~]# iperf3 -c
Connecting to host, port 5201
[  4] local port 41647 connected to port 5201

Oracle Database Cloud (DBaaS) Performance - Part 3 - Storage - 12.2 Update

Recently I repeated the I/O related tests on a instance for curiosity and was surprised by the fact that I consistently got significantly better results as on and

Now you're probably aware that the version 12.2 so far is "cloud-only", so I can't tell / test whether the version 12.2 is generically providing that increased performance or whether Oracle has optimized the underlying stack, so that previous versions in general could also benefit from better performance if they ran on the same platform. Repeated tests with versions and confirmed the performance figures reported in the previous installment of this series, so as of the time of writing it's only the version 12.2 that provides the improved I/O performance.

Note that as of the time of writing only a single instance configuration was supported with version 12.2, so I wasn't able to run the tests in RAC configuration.

Oracle Database Cloud (DBaaS) Performance - Part 2 - Storage

In this second part of this installment I'll focus on the performance figures related to I/O encountered when the corresponding tests were performed on the platform.


When running with minimum sized buffer cache, direct and asynchronous I/O enabled, the following average read-only IOPS figures were measured over a period of several days (this is the test described in part three of the "performance consistency" series) .

First, running on a 4 OCPU single instance configuration (8 CPUs / 8 cores as outlined in the previous part) with either four or eight sessions:

Oracle Database Cloud (DBaaS) Performance - Part 1 - CPU

After having looked at the performance consistency provided by the Oracle Database Cloud offering in the previous series, I'll focus here on the raw performance figures I've measured during my tests, starting with the CPU related performance findings.

One of the first surprises is related to the fact that Oracle uses a unit called "OCPU" to specify the CPU capacity provided, which is explained here:

Azure and Oracle Cloud – My First Time

Below talks about my experience trying out Azure and Oracle cloud for the very first time (and at the same time).

So last night I tried for the very 1st time the Azure and Oracle Cloud. Here, I just like to share my experience. BTW I am a big fan of DigitalOcean because of its user friendly interface, very fast to setup (end to end 2 minutes w/ few button clicks), and fantastic community and HOWTOs ( If I have to choose a cloud dev environment provider I would still use DigitalOcean.

Now, being a newbie on both these platforms. I’m looking for a similar experience as DigitalOcean.

The cloud experience comparison is broken down to 3 categories:

Oracle 12cR2: Database parameters

For those in a desperate need to learn all 4841 database parameter variations of the…

Oracle DBaaS database available

Just created my first Extreme Performance database in the So just after a…