Watermarks

May 20, 2025

Exploring Joins and Changelogs in Flink SQL

SQL. Three simple letters. Ess Queue Ell. /ˌɛs kjuː ˈɛl/.

In the data world they bind us together, yet separate us.

As the saying goes, England and America are two countries divided by the same language, and the same goes for the batch and streaming world and some elements of SQL.

Apr 25, 2025

It’s Time We Talked About Time: Exploring Watermarks (And More) In Flink SQL

Whether you’re processing data in batch or as a stream, the concept of time is an important part of accurate processing logic.

Because we process data after it happens, there are a minimum of two different types of time to consider:

When it happened, known as Event Time
When we process it, known as Processing Time (or system time or wall clock time)

Robin Moffatt

Robin Moffatt works on the DevRel team at Confluent. He likes writing about himself in the third person, eating good breakfasts, and drinking good beer.