pglockanalyze 

See what locks your Postgres migrations will acquire—before you run them in production.

To be used in CI and development environments; see pglockanalyze-action for integration with GitHub Actions.

Status

This software is in alpha stage - expect breaking changes between releases and a lot of rough edges.

Rationale

Understanding the locks your migrations will acquire is crucial to avoiding downtime in production traffic. Tools like the official Postgres docs and strong_migrations are invaluable; however, reasoning your way through complex DDL statements is not always practical.

pglockanalyze is meant to complement, not replace such tools, by executing your migrations against a test database (that you have to provision) and dynamically identifying the locks acquired at runtime. It then prints a report of the locks that were acquired.

By default, pglockanalyze rolls back the transactions it analyzes, so you can safely run it against a test database without worrying about leaving it in and inconsistent state. If you want to commit the transactions, you can use the --commit option.

Installation

You can install pglockanalyze using cargo:

$ cargo install pglockanalyze

We do not distribute binaries yet, but we may do so in the future.

Usage

$ echo 'ALTER TABLE users ALTER COLUMN name SET NOT NULL' | pglockanalyze --db 'postgres://foo@bar'
ALTER TABLE users ALTER COLUMN name SET NOT NULL
	acquired `AccessExclusive` lock on relation `users` (oid=16386)

Use --help to see all options:

Usage: pglockanalyze [OPTIONS] --db <postgres connection string> [INPUT]

Arguments:
  [INPUT]  The DDL statements to analyze. If not provided or is -, read from standard input [default: -]

Options:
      --db <postgres connection string>
          The database to connect to
  -f, --format <FORMATTER>
          The output format of the analysis [default: plain] [possible values: plain, json]
      --distinct-transactions
          Execute each statement in its own transaction. By default all statements are executed in a single transaction. Implies --commit
      --commit
          Commit the transactions. By default they are rolled back
  -h, --help
          Print help
  -V, --version
          Print version

License

pglockanalyze is licensed under the Apache 2.0 license.