squawk

Linter for Postgres migrations & SQL

Quick Start | Playground | Rules Documentation | GitHub Action | DIY GitHub Integration

Why?

Prevent unexpected downtime caused by database migrations and encourage best practices around Postgres schemas and SQL.

Install

npm install -g squawk-cli

# or via PYPI
pip install squawk-cli

# or install binaries directly via the releases page
https://github.com/sbdchd/squawk/releases

Or via Docker

You can also run Squawk using Docker. The official image is available on GitHub Container Registry.

# Assuming you want to check sql files in the current directory
docker run --rm -v $(pwd):/data ghcr.io/sbdchd/squawk:latest *.sql

Or via the Playground

Use the WASM powered playground to check your SQL locally in the browser!

https://play.squawkhq.com

Or via VSCode

https://marketplace.visualstudio.com/items?itemName=sbdchd.squawk

Usage

❯ squawk example.sql
warning[prefer-bigint-over-int]: using 32-bit integer fields can result in hitting the max `int` limit
  ╭▸ example.sql:6:10
  │
6 │     "id" serial NOT NULL PRIMARY KEY,
  │          ━━━━━━
  │
  ├ help: use 64-bit integer values instead to prevent hitting this limit
  ╭╴
6 │     "id" bigserial NOT NULL PRIMARY KEY,
  ╰╴         +++
warning[prefer-identity]: serial types make schema, dependency, and permission management difficult
  ╭▸ example.sql:6:10
  │
6 │     "id" serial NOT NULL PRIMARY KEY,
  │          ━━━━━━
  │
  ├ help: use an `identity` column instead
  ╭╴
6 -     "id" serial NOT NULL PRIMARY KEY,
6 +     "id" integer generated by default as identity NOT NULL PRIMARY KEY,
  ╰╴
warning[prefer-text-field]: changing the size of a `varchar` field requires an `access exclusive` lock, that will prevent all reads and writes to the table
  ╭▸ example.sql:7:13
  │
7 │     "alpha" varchar(100) NOT NULL
  │             ━━━━━━━━━━━━
  │
  ├ help: use a `text` field with a `check` constraint
  ╭╴
7 -     "alpha" varchar(100) NOT NULL
7 +     "alpha" text NOT NULL
  ╰╴
warning[require-concurrent-index-creation]: during normal index creation, table updates are blocked, but reads are still allowed
   ╭▸ example.sql:10:1
   │
10 │ CREATE INDEX "field_name_idx" ON "table_name" ("field_name");
   │ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
   │
   ├ help: use `concurrently` to avoid blocking writes
   ╭╴
10 │ CREATE INDEX concurrently "field_name_idx" ON "table_name" ("field_name");
   ╰╴             ++++++++++++
warning[constraint-missing-not-valid]: by default new constraints require a table scan and block writes to the table while that scan occurs
   ╭▸ example.sql:12:24
   │
12 │ ALTER TABLE table_name ADD CONSTRAINT field_name_constraint UNIQUE (field_name);
   │                        ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
   │
   ╰ help: use `not valid` with a later `validate constraint` call
warning[disallowed-unique-constraint]: adding a `unique` constraint requires an `access exclusive` lock which blocks reads and writes to the table while the index is built
   ╭▸ example.sql:12:28
   │
12 │ ALTER TABLE table_name ADD CONSTRAINT field_name_constraint UNIQUE (field_name);
   │                            ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
   │
   ╰ help: create an index `concurrently` and create the constraint using the index

Find detailed examples and solutions for each rule at https://squawkhq.com/docs/rules
Found 6 issues in 1 file (checked 1 source file)

squawk --help

Find problems in your SQL

Usage: squawk [OPTIONS] [path]... [COMMAND]

Commands:
  server            Run the language server
  upload-to-github  Comment on a PR with Squawk's results
  help              Print this message or the help of the given subcommand(s)

Arguments:
  [path]...
          Paths or patterns to search

Options:
      --exclude-path <EXCLUDED_PATH>
          Paths to exclude

          For example:

          `--exclude-path=005_user_ids.sql --exclude-path=009_account_emails.sql`

          `--exclude-path='*user_ids.sql'`

  -e, --exclude <rule>
          Exclude specific warnings

          For example: --exclude=require-concurrent-index-creation,ban-drop-database

  -i, --include <rule>
          Include opt-in rules that are disabled by default

          Rules listed in --exclude take precedence over --include.

          For example: --include=require-table-schema

      --pg-version <PG_VERSION>
          Specify postgres version

          For example: --pg-version=13.0

      --debug <format>
          Output debug format

          [possible values: lex, parse, ast]

      --reporter <REPORTER>
          Style of error reporting

          [possible values: tty, gcc, json, gitlab]

      --stdin-filepath <filepath>
          Path to use in reporting for stdin

      --verbose
          Enable debug logging output

  -c, --config <CONFIG_PATH>
          Path to the squawk config file (.squawk.toml)

      --assume-in-transaction
          Assume that a transaction will wrap each SQL file when run by a migration tool

          Use --no-assume-in-transaction to override any config file that sets this

      --no-error-on-unmatched-pattern
          Do not exit with an error when provided path patterns do not match any files

  -h, --help
          Print help (see a summary with '-h')

  -V, --version
          Print version

Rules

Individual rules can be disabled via the --exclude flag

squawk --exclude=adding-field-with-default,disallowed-unique-constraint example.sql

Disabling rules via comments

Rule violations can be ignored via the squawk-ignore comment:

-- squawk-ignore ban-drop-column
alter table t drop column c cascade;

You can also ignore multiple rules by making a comma seperated list:

-- squawk-ignore ban-drop-column, renaming-column,ban-drop-database
alter table t drop column c cascade;

To ignore a rule for the entire file, use squawk-ignore-file:

-- squawk-ignore-file ban-drop-column
alter table t drop column c cascade;
-- also ignored!
alter table t drop column d cascade;

Or leave off the rule names to ignore all rules for the file

-- squawk-ignore-file
alter table t drop column c cascade;
create table t (a int);

Configuration file

Rules can also be disabled with a configuration file.

By default, Squawk will traverse up from the current directory to find a .squawk.toml configuration file. You may specify a custom path with the -c or --config flag.

squawk --config=~/.squawk.toml example.sql

The --exclude flag will always be prioritized over the configuration file.

Example .squawk.toml

excluded_rules = [
    "require-concurrent-index-creation",
    "require-concurrent-index-deletion",
]

See the Squawk website for documentation on each rule with examples and reasoning.

Bot Setup

Squawk works as a CLI tool but can also create comments on GitHub Pull Requests using the upload-to-github subcommand.

Here's an example comment created by squawk using the example.sql in the repo:

https://github.com/sbdchd/squawk/pull/14#issuecomment-647009446

See the "GitHub Integration" docs for more information.

pre-commit hook

Integrate Squawk into Git workflow with pre-commit. Add the following to your project's .pre-commit-config.yaml:

repos:
  - repo: https://github.com/sbdchd/squawk
    rev: v2.71.0
    hooks:
      - id: squawk
        files: path/to/postgres/migrations/written/in/sql

Note the files parameter as it specifies the location of the files to be linted.

Prior Art / Related

• https://github.com/erik/squabble
• https://github.com/yandex/zero-downtime-migrations
• https://github.com/tbicr/django-pg-zero-downtime-migrations
• https://github.com/3YOURMIND/django-migration-linter
• https://github.com/ankane/strong_migrations
• https://github.com/AdmTal/PostgreSQL-Query-Lock-Explainer
• https://github.com/stripe/pg-schema-diff
• https://github.com/kristiandupont/schemalint
• https://github.com/supabase-community/postgres-language-server
• https://github.com/premium-minds/sonar-postgres-plugin
• https://engineering.fb.com/2022/11/30/data-infrastructure/static-analysis-sql-queries/
• https://github.com/xNaCly/sqleibniz
• https://github.com/sqlfluff/sqlfluff
• https://atlasgo.io/lint/analyzers
• https://github.com/tobymao/sqlglot
• https://github.com/paupino/pg_parse
• https://github.com/sql-formatter-org/sql-formatter
• https://github.com/darold/pgFormatter
• https://github.com/sqls-server/sqls
• https://github.com/joe-re/sql-language-server
• https://github.com/nene/sql-parser-cst
  • https://github.com/nene/prettier-plugin-sql-cst
• https://www.sqlstyle.guide
• https://github.com/ivank/potygen

Related Blog Posts / SE Posts / PG Docs

• https://www.braintreepayments.com/blog/safe-operations-for-high-volume-postgresql/
• https://gocardless.com/blog/zero-downtime-postgres-migrations-the-hard-parts/
• https://www.citusdata.com/blog/2018/02/22/seven-tips-for-dealing-with-postgres-locks/
• https://realpython.com/create-django-index-without-downtime/#non-atomic-migrations
• https://dba.stackexchange.com/questions/158499/postgres-how-is-set-not-null-more-efficient-than-check-constraint
• https://www.postgresql.org/docs/10/sql-altertable.html#SQL-ALTERTABLE-NOTES
• https://www.postgresql.org/docs/current/explicit-locking.html
• https://benchling.engineering/move-fast-and-migrate-things-how-we-automated-migrations-in-postgres-d60aba0fc3d4
• https://medium.com/paypal-tech/postgresql-at-scale-database-schema-changes-without-downtime-20d3749ed680

Dev

cargo install
cargo run
./s/test
./s/lint
./s/fmt

... or with nix:

$ nix develop
[nix-shell]$ cargo run
[nix-shell]$ cargo insta review
[nix-shell]$ ./s/test
[nix-shell]$ ./s/lint
[nix-shell]$ ./s/fmt

Adding a New Rule

When adding a new rule, running cargo xtask new-rule will create stubs for your rule in the Rust crate and in Documentation site.

cargo xtask new-rule 'prefer big serial'

Releasing a New Version

1. Run s/update-version

   # update version in squawk/Cargo.toml, package.json, flake.nix to 4.5.3
   s/update-version 4.5.3
   

2. Update the CHANGELOG.md

   Include a description of any fixes / additions. Make sure to include the PR numbers and credit the authors.

3. Create a new release on GitHub

   Use the text and version from the CHANGELOG.md

Algolia

The squawkhq.com Algolia index can be found on the crawler website. Algolia reindexes the site every day at 5:30 (UTC).

How it Works

Squawk uses its parser (based on rust-analyzer's parser) to create a CST. The linters then use an AST layered on top of the CST to navigate and record warnings, which are then pretty printed!