Everything our consultants learn while running databases for customers: Oracle, PostgreSQL, SQL Server, MySQL, MariaDB, MongoDB and Delphix. Expect hands-on posts about installation, day-to-day administration, backup and recovery, performance tuning, replication and upgrades.
Introduction Oracle Database Appliances rely on ASM to manage disk redundancy. And ASM is brilliant. Compared to RAID, redundancy is managed at the block level. For NORMAL redundancy, which is similar to RAID1, you need at least 2 disks, but it can also work with 3 disks, 4 disks, 5 disks and so on. There is no need for parity…
In this blog post, I will share with you a small PowerShell script I did recently. I have noticed that my customer performs a very repetitive and time-consuming task almost every day. New columns are added to tables on their business-critical database and they need to maintain SQL scripts file with all the ALTER TABLE statements for each new column.…
Introduction Oracle Database Appliances are very popular these days. And not only among new customers for this kind of engineered systems. Almost all customers already using old generation ODAs are renewing their infrastructure by choosing again ODAs, meaning that the solution is good enough and probably better than anything else. But now, public clouds are a real alternative to on-premise…
In this blog I want to introduce you to a workaround for a performance issue which randomly appeared during the upgrades of several Oracle 12c databases to 19c I performed for a financial services provider. During the upgrades we ran into a severe performance issue after the upgrades of more than 40 databases had worked just fine. While most of…
As of now, all the previous posts worked with the Community Edition of Exasol. While that is great for getting started quickly (the Community Edition comes with all the features, except multi node support and a limit of 200GB of data) there are some limitations: Can you not really test how data is distributed across cluster nodes because there is…
I made a mistake recently when adding a new node to an existing Windows Failover Cluster supporting AlwaysOn SQL Server instances. When adding a new node using the GUI there’s this option checked by default named “Add all eligible storage to the cluster”. Before performing the operation the disks on the 2 nodes of my cluster were used by the…
I have been recently deploying some new ODA X8-2-HA. After reimaging and creating the appliance, I had to patch the ODA. The day after, checking status, I could realize that my node 0 was not working as expected. I did some interesting troubleshooting that I wanted to share hoping it might be helpful for someone. Why patching an ODA after…
In the previous post we did the groundwork for being able to backup the Exasol database to an S3 bucket. We learned that you can do full level 0 backups and of top of that you can do incremental backups, that refer to each other. A restore of the full backup worked fine and pretty fast. In this post we’ll…
By Franck Pachot . The NoSQL technologies emerged for Big Data workloads where eventual consistency is acceptable and scaling out to multiple server nodes is an easy answer to increase throughput. With cloud services rising, those key-value document datastores started to be used by the web-scale companies for some transactional processing workloads as well. The solutions can provide high performance…
Now that we have a system with a proper network setup we can take a look at how backup and restore works in Exasol. Without being able to restore and recover your database, you for sure cannot put a system into production, so backup and restore always is a major topic to understand (with any system that holds data you…
Initially I wanted to write about Backup and Restore of Exasol databases but I quickly ran into issues, and this is the reason why this post is coming first. When you import the Exasol Community OVA as described in the first post, the VM is running with host only adapters and you can not connect to anything outside the Exasol…
By Franck Pachot . Statistically, my blog posts starting with a single SQL keyword (like COMMIT and ROLLBACK) in the title are not fully technical ones, but about moves. Same here. It is more about community engagement, people sharing. And about a friend. And clusters of course… In 2020 because of this COVID virus, we try to avoid clusters of…
