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Ansible tips’n’tricks: provision multiple machines in parallel with Vagrant and Ansible

Vagrant is a great tool that I’m regularly using for building playground environments on my laptop. I recently came across a slight inconvenience with Vagrant’s Virtualbox provider: occasionally I would like to spin up a Data Guard environment and provision both VMs in parallel to save time. Sadly you can’t bring up multiple machines in parallel using the VirtualBox provisioner according to the documentation . This was true as of April 11 2019 and might change in the future, so keep an eye out on the reference.

I very much prefer to save time by doing things in parallel, and so I started digging around how I could achieve this goal.

SSIS vs. Oracle GG

This is the third in a series of product identifications between Oracle and Microsoft to assist those attempting to understand the similarities and differences between these essential parts of any data platform environments.

In this post, I’m going to describe the similarities and differences between Microsoft SQL Server Integration Services and Oracle Golden Gate. Hang on, it’s a bit of a bumpy ride. as neither service is out there on its own, (other’s piggy back off of them) and there’s definitely some new products on the Microsoft side that aren’t taken into consideration.

Describe Upgrade

Here’s an odd little change between Oracle versions that could have a stunning impact on the application performance if the thing that generates your client code happens to use an unlucky selection of constructs.  It’s possible to demonstrate the effect remarkably easily – you just have to describe a table, doing it lots of times to make it easy to see what’s happening.

19c EM Express (aka Oracle Cloud Database Express)

Oracle has a long history of interactive tools for DBA and, as usual, the name has changed at each evolution for marketing reasons.

OEM in Oracle7 #nostalgia

SQL*DBA had a Menu mode for text terminals. You may also remember DBA Studio. Then called Oracle Enterprise Manager with its SYSMAN repository and also referred to as OEM or EM. The per-database version has been called OEM “Database Control” and then “EM Express” in 12c. The multi-database version has been called according to the marketing tag “Grid Control” in 11g, and “Cloud Control” in 12c.

19c EZCONNECT and Wallet (Easy Connect and External Password File)

I like EZCONNECT because it is simple when we know the host:port, and I like External Password Files because I hate to see passwords in clear text. But the combination of the two was not easy before 19c.

Of course, you can add a wallet entry for an EZCONNECT connection string, like ‘//localhost/PDB1’ but in the wallet, you need a different connection string for each user because it associates a user and password to a service name. And you have multiple users connecting to a service.

Here is an example. I have a user DEMO with password MyDemoP455w0rd:

Oracle RAC vs. SQL Server AG

As I have seen the benefit for having a post on Oracle database vs. SQL Server architecture, let’s move onto the next frontier- High Availability…or what people think is high availability architecture in the two platforms.

To RAC or Not to RAC

There is a constant rumble among Oracle DBAs- either all-in for Oracle Real Application Cluster, (RAC) or a desire to use it for the tool it was technically intended for. Oracle RAC can be very enticing- complex and feature rich, its the standard for engineered systems, such as Oracle Exadata and even the Oracle Data Appliance, (ODA). Newer implementation features, such as Oracle RAC One-Node offered even greater flexibility in the design of Oracle environments, but we need to also discuss what it isn’t- Oracle RAC is not a Disaster Recovery solution.

Stats advisor

This is just a little shout-out about the Stats Advisor – if you decide to give it a go, what sort of things is it likely to tell you. The answer is in a dynamic performance view called v$stats_advisor_rules – which I’ve list below from an instance running

Lost time

Here’s a little puzzle that came up in the ODC database forum yesterday – I’ve got a query that has been captured by SQL Monitor, and it’s taking much longer to run than it should but the monitoring report isn’t telling me what I need to know about the time.

Here’s a little model to demonstrate the problem – I’m going to join a table to itself (the self join isn’t a necessary feature of the demonstration, I’ve just been a bit lazy in preparing data). Here’s a (competely truthful) description of the table:

Oracle vs. SQL Server Architecture

There are a lot of DBAs that are expected to manage both Oracle and MSSQL environments. This is only going to become more common as database platforms variations with the introduction of the cloud continue. A database is a database in our management’s world and we’re expected to understand it all.

Its not an easy topic, but I’m going to post on it, taking it step by step and hopefully the diagrams will help. Its also not an apple to apple comparison, so hopefully, but starting at the base and working my way into it with as similar as comparisons as I’m able to with features, it will make sense for those out there that need to understand it.

We have a number of customers that are migrating Oracle to Azure and many love Oracle and want to keep their Oracle database as is, just bringing their licenses over to the cloud. The importance of this is they may have Azure/SQL DBAs managing them, so I’m here to help.


A few months ago Franck Pachot wrote about a recursive SQL statement that kept appearing in the library cache. I discovered the note today because I had just found a client site where the following statement suddenly appeared near the top of the “SQL ordered by Executions” section of their AWR reports after they had upgraded to 18c.

select domain# from sys.im_domain$ where objn = :1 and col# = :2

I found Franck’s article by the simple expedient of typing the entire query into a Google search – his note was the first hit on the list, and he had a convenient example (based on the SCOTT schema) to demonstrate the effect, so I built the tables from the schema and ran a simple test with extended SQL tracing (event 10046) enabled.