PerfettoSQL Style Guide

This page provides a suggested style guide for writing PerfettoSQL and is in use inside the PerfettoSQL standard library in the trace processor. It also provides guidance on the autoformatter.

Rules

1. Keep lines below 80 characters long
2. Function names, macro names and table/view names should all be lower snake case.
3. SQL keywords should all be upper case
4. When line-breaking SQL expressions, place the joining keyword (AND/OR) at the start of the next line rather than the end of the previous line.

Autoformatter

PerfettoSQL comes with an auto-formatter as implemented by tools/format_sql.py Python script. This is a simple script which can be run over any set of files or directories and automatically formats the code to adhere to the above rules.

This script is required to be run when making contributions to the standard library. It's automatically executed as part of running tools/gen_all which is part of the standard development workflow in Perfetto. Presubmit will check to make sure you've done this.

The autoformatter is not perfect by any means and does often have subtle edge cases:

1. It doesn't handle comments in the middle of complex expressions. Prefer placing comments at the start of these expressions instead of in the middle.
2. It doesn't format macro invocations as they have very complex semantics in many cases.