Oracle 19c on LiveSQL

I used to write about the Oracle free service for developers livesql.oracle.com in the past. For those who work with Oracle databases and haven’t tested it I recommend go and try. It runs with a “SQL Developer like” interface with the ability to test syntax for your SQL queries, packages or procedures and provide a space where you can create small tables and try different things. Also, you have access to some shared example schema with data which can be used in your demonstrations and tests. The service runs on an Oracle Exadata hardware, supports HCC compression and uses the latest Oracle database software. And the version of the database software is the main topic of this today’s small post.
Today is the middle of January of 2019. We all know the Oracle naming for new versions of software reflects the year when it is issued. And today in the very first month of the new 2019 year we already can try shiny, new Oracle Database 19c. You have already guessed how you can do it. Continue reading “Oracle 19c on LiveSQL”

First Touch Penalty On AWS Cloud

(first time published in March 2018 some information may not be correct anymore)
A couple of weeks ago I had a discussion about AWS RDS with one of my colleagues and he mentioned some unexpected IO problem during migration. It was during production cutover when they switched from the old environment on-prem to the freshly restored database on RDS. The migration itself is out of scope for the today’s topic. We are going to point our attention to the unexpected IO problem. They should have plenty of IO bandwidth and everything was totally fine when they tested it before, but somehow many of the queries to the database were performing extremely slow for around 30 or 40 minutes and even after that they observed sporadic spikes in the number of sessions waiting for IO. After a couple of additional questions, it was more or less clear that they most likely hit a known problem described in AWS documentation. I am talking about “First touch penalty” on AWS. For this topic, I will use an Oracle RDS database to demonstrate the issue and how you can prepare for it. Continue reading “First Touch Penalty On AWS Cloud”