Housekeeping in Oracle: How to Get Rid of Old Data
Have you ever tried to delete a few million rows from a table with several hundred milllions of rows with a DELETE statement? If yes, then you know that this is a very bad idea. With Oracle Partitioning you can do this more elegant and…
NVMes write back vs. write through performance
Recently I was running some benchmarks to double-check that the performance of AMD EPYCs servers delivered by Company A, match the performance of those delivered by Company B. I was using our benchmark automation tool (about which I may write a bit more in the…
Data Vault versus Database Vault
In the Oracle community, the terms “Data Vault” and “Database Vault” are often confused, although they have nothing to do with each other. A short clarification. Some time ago I had a meeting with the development team and the database administrator of one of my…
Performance Tips: PL/SQL Functions in SQL Queries
PL/SQL functions in SQL statements may cause major performance problems. If it is not possible to avoid these calls, there are several solutions to improve the performance. But not for all situations. In my last blog post, I wrote about the impact of function calls in…
GoldenGate: Initial Load DB2 to Oracle and HANDLECOLLSIONS
In this blog post I mainly want to discuss the GoldenGate parameter HANDLECOLLISIONS and do some tests to find out about its reliability. I always felt very uncomfortable whenever I needed to use it. So this post is also about the desire for trust in…
Important behaviour change between bash version 4.3 and 4.4
Please be aware about important behaviour change between bash version 4.3 and 4.4. You can observe it for example while migrating from Oracle Linux 7 to 8/CentOS 7 to Rocky Linux 8/etc. as version 7 of RHEL compatible system comes with bash 4.2, whereas version…
Performance Tips: Function Calls in WHERE Conditions
A typical reason of many performance issues with SQL are function calls in the WHERE condition. They make it difficult for the query optimizer to determine the cardinality. Fortunately, there are several ways to solve this problem. Function calls – or any kind of SQL expressions…
Finding Wrong Hints
Introduction I use the Oracle Database since many years. And I use hints. For experiments, but also in production code. There are cases when you know more than the Oracle Database. For example about the cardinality of a data source or the number of result…
2021: Another Year at Home
I never wrote so few blog posts like in 2021. There are several reasons for this. But there are also good news: I was able to attend at least a few conferences this year. As you can see in my blog, I wrote very few…
GraalVM Native Image – First Impressions
Introduction A native image is an operating system specific executable file. You can build such an image for basically every application running on a Java virtual machine. This approach promises faster start-up times and lower resource consumptions. This makes it appealing for serverless computing, auto-scaling…