What is Schema Tracking? # In a distributed relational database system, like Vitess, a central component is responsible for serving queries across multiple shards. For Vitess, it is VTGate. One of the challenges this component faces is being aware of the underlying SQL schema being used. This awareness facilitates query planning. Table schemas are stored in MySQL’s information_schema, meaning that they are located in a VTTablet’s MySQL instance and not in VTGate.
Background # A critical vulnerability CVE-2021-44228 in the Apache Log4j logging library was disclosed on Dec 9. The project provided release 2.15.0 with a patch that mitigates the impact of this CVE. It was quickly found that the initial patch was insufficient, and an additional CVE CVE-2021-45046 followed. This has been fixed in release 2.16.0. Who is affected? # The bulk of vitess code is in golang, and is unaffected by these vulnerabilities.