sqlfmt

An opinionated SQL formatter written in Rust. Optimized for Snowflake and DuckDB.

Installation

Build from source

git clone https://github.com/athvin/sqlfmt.git
cd sqlfmt
cargo install --path .

Usage

Format files or directories in place:

sqlfmt .
sqlfmt queries/
sqlfmt path/to/query.sql

Read from stdin, write to stdout:

echo "SELECT   a,b FROM t WHERE x=1" | sqlfmt -

Check formatting without modifying files (exit code 1 if changes needed):

sqlfmt --check .

Show a diff of what would change:

sqlfmt --diff .

Options

Usage: sqlfmt [OPTIONS] <FILES>...

Arguments:
  <FILES>...  Files or directories to format. Use "-" to read from stdin

Options:
  -l, --line-length <LINE_LENGTH>  Maximum line length [default: 88]
  -d, --dialect <DIALECT>          SQL dialect: polyglot, duckdb [default: polyglot]
      --check                      Check formatting without writing changes
      --diff                       Show formatting diff
      --fast                       Skip safety equivalence check (faster)
      --no-jinjafmt                Disable Jinja template formatting
      --exclude <EXCLUDE>          Glob patterns to exclude
  -v, --verbose                    Verbose output
  -q, --quiet                      Quiet output (errors only)
  -t, --threads <THREADS>          Number of threads for parallel processing (0 = all cores) [default: 0]
      --single-process             Disable multi-threaded processing
      --config <CONFIG>            Path to config file (pyproject.toml or sqlfmt.toml)
  -h, --help                       Print help
  -V, --version                    Print version

Environment variables

You can set environment variables to configure behavior without passing flags on every invocation:

Variable	Equivalent flag	Description
SQLFMT_FAST=1	--fast	Skip the safety equivalence check for faster formatting
SQLFMT_THREADS=N	--threads N	Number of parallel threads (0 = all cores)
SQLFMT_STRICT_WHITESPACE=1	(no flag)	Treat whitespace-only input as a parsing error instead of returning empty output

Accepted values for boolean variables (SQLFMT_FAST, SQLFMT_STRICT_WHITESPACE): 1, true, yes (case-insensitive). CLI flags always take precedence over environment variables.

# Format a large directory as fast as possible
export SQLFMT_FAST=1
export SQLFMT_THREADS=8
sqlfmt .

Configuration file

sqlfmt reads settings from sqlfmt.toml or the [tool.sqlfmt] section of pyproject.toml. The file is auto-discovered by searching parent directories of the files being formatted.

# sqlfmt.toml
line_length = 100
dialect = "duckdb"
exclude = ["migrations/**"]
no_jinjafmt = true

Option	Type	Description	Default
line_length	integer	Maximum line length	88
dialect	string	SQL dialect (polyglot or duckdb)	polyglot
exclude	array of strings	Glob patterns to exclude	[]
no_jinjafmt	boolean	Disable Jinja template formatting	false

Performance

Each SQL file is an independent unit of work. sqlfmt dispatches every file to a worker that handles read → format → write end-to-end. By default it uses all available cores; use --threads N to limit concurrency.

sqlfmt -t 8 .              # Limit to 8 workers
sqlfmt --single-process .  # Single-threaded

For maximum speed on large directories, combine with --fast to skip the safety equivalence check:

sqlfmt --fast .