Row-By-Row Is Slow-By-Slow

Lukas Eder points out that row-by-row updates are a great way of slowing down your system:

The best way to find out is to benchmark. I’m doing two benchmarks for this:

1. One that is run in PL/SQL, showing the performance difference between different approaches that are available to PL/SQL (namely looping, the FORALL syntax, and a single bulk UPDATE)

2. One that is run in Java, doing JDBC calls, showing the performance difference between different approaches available to Java (namely looping, caching PreparedStatement but still looping, batching, and a single bulk UPDATE)

The results tend to be even more dramatic on SQL Server, where the row-by-row overhead is even greater.