# squawk [](https://www.npmjs.com/package/squawk-cli)
> Linter for Postgres migrations & SQL
## Why?
Prevent unexpected downtime caused by database migrations and encourage best
practices around Postgres schemas and SQL.
## Install
```shell
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.
```shell
# 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
```shell
❯ 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`
```
squawk
Find problems in your SQL
USAGE:
squawk [FLAGS] [OPTIONS] [path]... [SUBCOMMAND]
FLAGS:
--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 this setting in any config file that exists
-h, --help
Prints help information
-V, --version
Prints version information
--verbose
Enable debug logging output
OPTIONS:
-c, --config <config-path>
Path to the squawk config file (.squawk.toml)
--debug <format>
Output debug info [possible values: Lex, Parse]
--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
--pg-version <pg-version>
Specify postgres version
For example: --pg-version=13.0
--reporter <reporter>
Style of error reporting [possible values: Tty, Gcc, Json]
--stdin-filepath <filepath>
Path to use in reporting for stdin
ARGS:
<path>...
Paths to search
SUBCOMMANDS:
help Prints this message or the help of the given subcommand(s)
upload-to-github Comment on a PR with Squawk's results
```
## Rules
Individual rules can be disabled via the `--exclude` flag
```shell
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:
```sql
-- squawk-ignore ban-drop-column
alter table t drop column c cascade;
```
You can also ignore multiple rules by making a comma seperated list:
```sql
-- 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`:
```sql
-- 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
```sql
-- 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.
```shell
squawk --config=~/.squawk.toml example.sql
```
The `--exclude` flag will always be prioritized over the configuration file.
**Example `.squawk.toml`**
```toml
excluded_rules = [
"require-concurrent-index-creation",
"require-concurrent-index-deletion",
]
```
See the [Squawk website](https://squawkhq.com/docs/rules) 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](https://squawkhq.com/docs/github_app) for more information.
## `pre-commit` hook
Integrate Squawk into Git workflow with [pre-commit](https://pre-commit.com/). Add the following
to your project's `.pre-commit-config.yaml`:
```yaml
repos:
- repo: https://github.com/sbdchd/squawk
rev: v0.10.0
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
```shell
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.
```bash
cargo xtask new-rule 'prefer big serial'
```
### Releasing a New Version
1. Run `s/update-version`
```bash
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](https://crawler.algolia.com/admin/crawlers/9bf0dffb-bc5a-4d46-9b8d-2f1197285213/overview). 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!