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Database

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.

In which order do triggers fire in PostgreSQL?

When you are working with triggers it might be important to know in which order they fire. Of course, a “before” triggers fires before an “after” trigger. But what happens if you have two or more triggers for the same event? Maybe you want to make sure that a specific trigger is executed first (for whatever reason) or you want… 

How much shared memory is PostgreSQL using? (2) – details

In the last post in this two post series we’ve briefly looked at configuring huge pages on Linux for PostgreSQL. It became clear, that calculating the number of huge pages purely based on the setting of shared_buffers will not work. PostgreSQL requires more shared memory, but what exactly is it? Well, this is the goal of this post and I’ll… 

How much shared memory is PostgreSQL using? (1) – basics

Have you ever wondered if the value of shared_buffers is the only setting which controls how much shared memory PostgreSQL is actually using? There was a nice addition committed to PostgreSQL 15 recently, which helps in answering this question (more on that later). shared_buffers for sure is the biggest chunk of shared memory that PostgreSQL is using but there might… 

MongoDB Monitoring using Nagios

The question comes frequently: How can I monitor my MongoDB cluster (ReplicaSet or Sharded) in a production environment? To answer this question we need first to get an overview of all potential monitoring solutions, and then compare them one by one. That’s exactly what we gonna do in this blog post series of MongoDB Monitoring solutions. Actually, a few monitoring… 

Temporal tables for PostgreSQL 15?

One of the features which is currently missing in PostgreSQL is Temporal Tables. Other database systems have that since a long time and many people want to have in PostgreSQL as well. If you don’t know what it is, here is a short overview. Basically you can ask for a row as it was at a specific point in time.… 

Parallel distinct for PostgreSQL 15

When parallel execution was introduced with PostgreSQL 9.6 it was quite limited and supported only a few operations to run in parallel. Over time more and more operations were enabled to run in parallel. When PostgreSQL 15 will be released next year it will come with parallel distinct. Here is an easy example: If you do something like this, e.g.… 

What are those *_init files for in PostgreSQL?

Quite some time ago I’ve written about relation files in PostgreSQL and when they get created. In that post we talked about the files containing the actual data, the free space map (fsm) and the visibility map (vm). But this is not all, there is another kind of file you might spot if you take a look into the directory… 

How to find the TLS used for the SQL Server connection

For a customer, I do some research to find which TLS is used on the SQL Server environment. The only way is to create an Extended Event. A big limitation is that the event used is only available on SQL Server 2016 and +. Before use the Built-In Diagnostics (BID) traces. After I implanted the first TLS Monitoring on  a… 

How to view and change SQL Server Agent properties with T-SQL queries

Few days ago, after a reboot, we had this warning on the Agent Error Logs on many servers: Warning [396] An idle CPU condition has not been defined – OnIdle job schedules will have no effect “The CPU idle definition influences how Microsoft SQL Server Agent responds to events. For example, suppose that you define the CPU idle condition as… 

Auto Upgrade of non CDB to PDB with autoupgrade.jar in Oracle 21c

Since Oracle 21c it is possible to convert the non CDB database into a PDB directly during the upgrade using the Oracle Autoupgrade Tool. This is an important enhancement, because with Oracle 21c the non CDB architecture is desupported, which means that with an upgrade to 21c a conversion is mandatory. Let’s test if this new feature really works and…