@@ -2,55 +2,56 @@
22
33[](https://github.com/fabianlindfors/reshape/actions/workflows/test.yaml) [](https://github.com/fabianlindfors/reshape/releases)
44
5+> Also check out [ReshapeDB](https://reshapedb.com), a new database built from the ground up to make zero-downtime schema and data migrations as simple and safe as possible. If you'd like to chat about it, please [reach out](contact@reshapedb.com)!
6+
57Reshape is an easy-to-use, zero-downtime schema migration tool for Postgres. It automatically handles complex migrations that would normally require downtime or manual multi-step changes. During a migration, Reshape ensures both the old and new schema are available at the same time, allowing you to gradually roll out your application. It will also perform all changes without excessive locking, avoiding downtime caused by blocking other queries. For a more thorough introduction to Reshape, check out the [introductory blog post](https://fabianlindfors.se/blog/schema-migrations-in-postgres-using-reshape/).
68
79Designed for Postgres 12 and later.
810
9−*Note: Reshape is **experimental** and should not be used in production. It can (and probably will) break your application.*
10−
1111- [How it works](#how-it-works)
1212- [Getting started](#getting-started)
13− - [Installation](#installation)
14− - [Creating your first migration](#creating-your-first-migration)
15− - [Preparing your application](#preparing-your-application)
16− - [Running your migration](#running-your-migration)
17− - [Using during development](#using-during-development)
13+ - [Installation](#installation)
14+ - [Creating your first migration](#creating-your-first-migration)
15+ - [Preparing your application](#preparing-your-application)
16+ - [Running your migration](#running-your-migration)
17+ - [Using during development](#using-during-development)
1818- [Writing migrations](#writing-migrations)
19− - [Basics](#basics)
20− - [Tables](#tables)
21− - [Create table](#create-table)
22− - [Rename table](#rename-table)
23− - [Remove table](#remove-table)
24− - [Add foreign key](#add-foreign-key)
25− - [Remove foreign key](#remove-foreign-key)
26− - [Columns](#columns)
27− - [Add column](#add-column)
28− - [Alter column](#alter-column)
29− - [Remove column](#remove-column)
30− - [Indices](#indices)
31− - [Add index](#add-index)
32− - [Remove index](#remove-index)
33− - [Enums](#enums)
34− - [Create enum](#create-enum)
35− - [Remove enum](#remove-enum)
19+ - [Basics](#basics)
20+ - [Tables](#tables)
21+ - [Create table](#create-table)
22+ - [Rename table](#rename-table)
23+ - [Remove table](#remove-table)
24+ - [Add foreign key](#add-foreign-key)
25+ - [Remove foreign key](#remove-foreign-key)
26+ - [Columns](#columns)
27+ - [Add column](#add-column)
28+ - [Alter column](#alter-column)
29+ - [Remove column](#remove-column)
30+ - [Indices](#indices)
31+ - [Add index](#add-index)
32+ - [Remove index](#remove-index)
33+ - [Enums](#enums)
34+ - [Create enum](#create-enum)
35+ - [Remove enum](#remove-enum)
36+ - [Custom](#custom)
37+ - [Complex changes across tables](#complex-changes-across-tables)
3638- [Commands and options](#commands-and-options)
37− - [`reshape migrate`](#reshape-migrate)
38− - [`reshape complete`](#reshape-complete)
39− - [`reshape abort`](#reshape-abort)
40− - [`reshape generate-schema-query`](#reshape-generate-schema-query)
41− - [Connection options](#connection-options)
39+ - [`reshape migration start`](#reshape-migration-start)
40+ - [`reshape migration complete`](#reshape-migration-complete)
41+ - [`reshape migration abort`](#reshape-migration-abort)
42+ - [`reshape schema-query`](#reshape-schema-query)
43+ - [Connection options](#connection-options)
4244- [License](#license)
4345
44−
4546## How it works
4647
4748Reshape works by creating views that encapsulate the underlying tables, which your application will interact with. During a migration, Reshape will automatically create a new set of views and set up triggers to translate inserts and updates between the old and new schema. This means that every deployment is a three-phase process:
4849
49−1. **Start migration** (`reshape migrate`): Sets up views and triggers to ensure both the new and old schema are usable at the same time.
50+1. **Start migration** (`reshape migration start`): Sets up views and triggers to ensure both the new and old schema are usable at the same time.
50512. **Roll out application**: Your application can be gradually rolled out without downtime. The existing deployment will continue using the old schema whilst the new deployment uses the new schema.
51−3. **Complete migration** (`reshape complete`): Removes the old schema and any intermediate data and triggers.
52+3. **Complete migration** (`reshape migration complete`): Removes the old schema and any intermediate data and triggers.
5253
53−If the application deployment fails, you should run `reshape abort` which will roll back any changes made by `reshape migrate` without losing data.
54+If the application deployment fails, you should run `reshape migration abort` which will roll back any changes made by `reshape migration start` without losing data.
5455
5556## Getting started
5657
@@ -62,7 +63,7 @@ Binaries are available for macOS and Linux under [Releases](https://github.com/f
6263
6364#### Cargo
6465
65−Reshape can be installed using [Cargo](https://doc.rust-lang.org/cargo/):
66+Reshape can be installed using [Cargo](https://doc.rust-lang.org/cargo/) (requires Rust 1.58 or later):
6667
6768```shell
6869cargo install reshape
@@ -70,10 +71,10 @@ cargo install reshape
7071
7172#### Docker
7273
73−Reshape is available as a Docker image on [Docker Hub](https://hub.docker.com/repository/docker/fabianlindfors/reshape).
74+Reshape is available as a Docker image on [Docker Hub](https://hub.docker.com/repository/docker/fabianlindfors/reshape).
7475
7576```shell
76−docker run -v $(pwd):/usr/share/app fabianlindfors/reshape reshape migrate
77+docker run -v $(pwd):/usr/share/app fabianlindfors/reshape reshape migration start
7778```
7879
7980### Creating your first migration
@@ -102,9 +103,14 @@ This is the equivalent of running `CREATE TABLE users (id INTEGER GENERATED ALWA
102103
103104### Preparing your application
104105
105−Reshape relies on your application using a specific schema. When establishing the connection to Postgres in your application, you need to run a query to select the most recent schema. This query can be generated using: `reshape generate-schema-query`.
106+Reshape relies on your application using a specific schema. When establishing the connection to Postgres in your application, you need to run a query to select the most recent schema. The simplest way to do this is to use one of the helper libraries:
107+
108+- [Rust](https://github.com/fabianlindfors/reshape-helper)
109+- [Ruby (and Rails)](https://github.com/fabianlindfors/reshape-ruby)
110+- [Python (and Django)](https://github.com/fabianlindfors/reshape-python)
111+- [Go](https://github.com/leourbina/reshape-helper)
106112
107−To pass it along to your application, you can for example use an environment variable in your run script: `RESHAPE_SCHEMA_QUERY=$(reshape generate-schema-query)`. Then in your application:
113+If your application is not using one of the languages with an available helper library, you can instead generate the query with the command: `reshape schema-query`. To pass it along to your application, you can for example use an environment variable in your run script: `RESHAPE_SCHEMA_QUERY=$(reshape schema-query)`. Then in your application:
108114
109115```python
110116# Example for Python
@@ -117,16 +123,16 @@ db.execute(reshape_schema_query)
117123To create your new `users` table, run:
118124
119125```bash
120−reshape migrate
126+reshape migration start --complete
121127```
122128
123−As this is the first migration, Reshape will automatically complete it. For subsequent migrations, you will need to first run `reshape migrate`, roll out your application and then complete the migration using `reshape complete`.
129+We use the `--complete` flag to automatically complete the migration. During a production deployment, you should first run `reshape migration start` followed by `reshape migration complete` once your application has been fully rolled out.
124130
125131If nothing else is specified, Reshape will try to connect to a Postgres database running on `localhost` using `postgres` as both username and password. See [Connection options](#connection-options) for details on how to change the connection settings.
126132
127133### Using during development
128134
129−When adding new migrations during development, we recommend running `reshape migrate` but skipping `reshape complete`. This way, the new migrations can be iterated on by updating the migration file and running `reshape abort` followed by `reshape migrate`.
135+When adding new migrations during development, we recommend running `reshape migration start` but skipping `reshape migration complete`. This way, the new migrations can be iterated on by updating the migration file and running `reshape migration abort` followed by `reshape migration start`.
130136
131137## Writing migrations
132138
@@ -161,9 +167,9 @@ Every action has a `type`. The supported types are detailed below.
161167
162168#### Create table
163169
164−The `create_table` action will create a new table with the specified columns, indices and constraints.
170+The `create_table` action will create a new table with the specified columns, indices and constraints. You can optionally provide an `up` option to backfill values from an existing table.
165171
166−*Example: create a `customers` table with a few columns and a primary key*
172+_Example: create a `customers` table with a few columns and a primary key_
167173
168174```toml
169175[[actions]]
@@ -181,13 +187,13 @@ primary_key = ["id"]
181187 type = "TEXT"
182188
183189 # Columns default to nullable
184− nullable = false
190+ nullable = false
185191
186192 # default can be any valid SQL value, in this case a string literal
187− default = "'PLACEHOLDER'"
193+ default = "'PLACEHOLDER'"
188194```
189195
190−*Example: create `users` and `items` tables with a foreign key between them*
196+_Example: create `users` and `items` tables with a foreign key between them_
191197
192198```toml
193199[[actions]]
@@ -220,11 +226,34 @@ primary_key = ["id"]
220226 referenced_columns = ["id"]
221227```
222228
229+_Example: create `profiles` table based on existing `users` table_
230+
231+```toml
232+[[actions]]
233+type = "create_table"
234+name = "profiles"
235+primary_key = ["user_id"]
236+
237+ [[actions.columns]]
238+ name = "user_id"
239+ type = "INTEGER"
240+
241+ [[actions.columns]]
242+ name = "user_email"
243+ type = "TEXT"
244+
245+ # Backfill from `users` table and copy `users.email` to `user_email` column
246+ # This will perform an upsert based on the primary key to avoid duplicate rows
247+ [actions.up]
248+ table = "users"
249+ values = { user_id = "id", user_email = "email" }
250+```
251+
223252#### Rename table
224253
225254The `rename_table` action will change the name of an existing table.
226255
227−*Example: change name of `users` table to `customers`*
256+_Example: change name of `users` table to `customers`_
228257
229258```toml
230259[[actions]]
@@ -237,7 +266,7 @@ new_name = "customers"
237266
238267The `remove_table` action will remove an existing table.
239268
240−*Example: remove `users` table*
269+_Example: remove `users` table_
241270
242271```toml
243272[[actions]]
@@ -249,7 +278,7 @@ table = "users"
249278
250279The `add_foreign_key` action will add a foreign key between two existing tables. The migration will fail if the existing column values aren't valid references.
251280
252−*Example: create foreign key from `items` to `users` table*
281+_Example: create foreign key from `items` to `users` table_
253282
254283```toml
255284[[actions]]
@@ -266,7 +295,7 @@ table = "items"
266295
267296The `remove_foreign_key` action will remove an existing foreign key. The foreign key will only be removed once the migration is completed, which means that your new application must continue to adhere to the foreign key constraint.
268297
269−*Example: remove foreign key `items_user_id_fkey` from `users` table*
298+_Example: remove foreign key `items_user_id_fkey` from `users` table_
270299
271300```toml
272301[[actions]]
@@ -279,9 +308,9 @@ foreign_key = "items_user_id_fkey"
279308
280309#### Add column
281310
282−The `add_column` action will add a new column to an existing table. You can optionally provide an `up` setting. This should be an SQL expression which will be run for all existing rows to backfill the new column.
311+The `add_column` action will add a new column to an existing table. You can optionally provide an `up` setting. This should be an SQL expression which will be run for all existing rows to backfill the new column. `up` may also reference another table to perform cross-table migrations (see ["Complex changes across tables"](#complex-changes-across-tables)).
283312
284−*Example: add a new column `reference` to table `products`*
313+_Example: add a new column `reference` to table `products`_
285314
286315```toml
287316[[actions]]
@@ -295,7 +324,7 @@ table = "products"
295324 default = "10"
296325```
297326
298−*Example: replace an existing `name` column with two new columns, `first_name` and `last_name`*
327+_Example: replace an existing `name` column with two new columns, `first_name` and `last_name`_
299328
300329```toml
301330[[actions]]
@@ -331,7 +360,7 @@ column = "name"
331360down = "first_name || ' ' || last_name"
332361```
333362
334−*Example: extract nested value from unstructured JSON `data` column to new `name` column*
363+_Example: extract nested value from unstructured JSON `data` column to new `name` column_
335364
336365```toml
337366[[actions]]
@@ -346,14 +375,33 @@ up = "data['path']['to']['value'] #>> '{}'"
346375 type = "TEXT"
347376```
348377
378+_Example: duplicate `email` column from `users` to `profiles` table_
379+
380+```toml
381+# `profiles` has `user_id` column which maps to `users.id`
382+[[actions]]
383+type = "add_column"
384+table = "profiles"
385+
386+ [actions.column]
387+ name = "email"
388+ type = "TEXT"
389+ nullable = false
390+
391+ # When `users` is updated in the old schema, we write the email value to `profiles`
392+ [actions.up]
393+ table = "users"
394+ value = "email"
395+ where = "user_id = id"
396+```
349397
350398#### Alter column
351399
352400The `alter_column` action enables many different changes to an existing column, for example renaming, changing type and changing existing values.
353401
354−When performing more complex changes than a rename, `up` and `down` must be provided. These should be SQL expressions which determine how to transform between the new and old version of the column. Inside those expressions, you can reference the current column value by the column name.
402+When performing more complex changes than a rename, `up` and `down` should be provided. These should be SQL expressions which determine how to transform between the new and old version of the column. Inside those expressions, you can reference the current column value by the column name.
355403
356−*Example: rename `last_name` column on `users` table to `family_name`*
404+_Example: rename `last_name` column on `users` table to `family_name`_
357405
358406```toml
359407[[actions]]
@@ -365,7 +413,7 @@ column = "last_name"
365413 name = "family_name"
366414```
367415
368−*Example: change the type of `reference` column from `INTEGER` to `TEXT`*
416+_Example: change the type of `reference` column from `INTEGER` to `TEXT`_
369417
370418```toml
371419[[actions]]
@@ -380,7 +428,7 @@ down = "CAST(reference AS INTEGER)" # Converts from text value to integer
380428 type = "TEXT" # Previous type was 'INTEGER'
381429```
382430
383−*Example: increment all values of an `index` column by one*
431+_Example: increment all values of an `index` column by one_
384432
385433```toml
386434[[actions]]
@@ -395,7 +443,22 @@ down = "index - 1" # Decrement to revert for old schema
395443 name = "index"
396444```
397445
398−*Example: change default value of `created_at` column to current time*
446+_Example: make `name` column not nullable_
447+
448+```toml
449+[[actions]]
450+type = "alter_column"
451+table = "users"
452+column = "name"
453+
454+# Use "N/A" for any rows that currently have a NULL name
455+up = "COALESCE(name, 'N/A')"
456+
457+ [actions.changes]
458+ nullable = false
459+```
460+
461+_Example: change default value of `created_at` column to current time_
399462
400463```toml
401464[[actions]]
@@ -409,11 +472,11 @@ column = "created_at"
409472
410473#### Remove column
411474
412−The `remove_column` action will remove an existing column from a table. You can optionally provide a `down` setting. This should be an SQL expression which will be used to determine values for the old schema when inserting or updating rows using the new schema. The `down` setting must be provided when the removed column is `NOT NULL` or doesn't have a default value.
475+The `remove_column` action will remove an existing column from a table. You can optionally provide a `down` setting. This should be an SQL expression which will be used to determine values for the old schema when inserting or updating rows using the new schema. `down` may also reference another table to perform cross-table migrations (see ["Complex changes across tables"](#complex-changes-across-tables)) . The `down` setting must be provided when the removed column is `NOT NULL` or doesn't have a default value.
413476
414477Any indices that cover the column will be removed.
415478
416−*Example: remove column `name` from table `users`*
479+_Example: remove column `name` from table `users`_
417480
418481```toml
419482[[actions]]
@@ -425,18 +488,34 @@ column = "name"
425488down = "'N/A'"
426489```
427490
491+_Example: remove `email` column from `users` table and use column from `profiles` table instead_
492+
493+```toml
494+[[actions]]
495+type = "remove_column"
496+table = "users"
497+column = "email"
498+
499+ # Our application will use the `profiles.email` column instead
500+ # For backwards compatibility, we will write back to the removed `email` column whenever `profiles` is changed
501+ [actions.down]
502+ table = "profiles"
503+ value = "profiles.email"
504+ where = "users.id = profiles.user_id"
505+```
506+
428507### Indices
429508
430509#### Add index
431510
432511The `add_index` action will add a new index to an existing table.
433512
434−*Example: create a `users` table with a unique index on the `name` column*
513+_Example: create a `users` table with a unique index on the `name` column_
435514
436515```toml
437516[[actions]]
438517type = "create_table"
439−table = "users"
518+name = "users"
440519primary_key = "id"
441520
442521 [[actions.columns]]
@@ -460,7 +539,7 @@ table = "users"
460539 unique = true
461540```
462541
463−*Example: add GIN index to `data` column on `products` table*
542+_Example: add GIN index to `data` column on `products` table_
464543
465544```toml
466545[[actions]]
@@ -479,7 +558,7 @@ table = "products"
479558
480559The `remove_index` action will remove an existing index. The index won't actually be removed until the migration is completed.
481560
482−*Example: remove the `name_idx` index*
561+_Example: remove the `name_idx` index_
483562
484563```toml
485564[[actions]]
@@ -493,7 +572,7 @@ index = "name_idx"
493572
494573The `create_enum` action will create a new [enum type](https://www.postgresql.org/docs/current/datatype-enum.html) with the specified values.
495574
496−*Example: add a new `mood` enum type with three possible values*
575+_Example: add a new `mood` enum type with three possible values_
497576
498577```toml
499578[[actions]]
@@ -506,7 +585,7 @@ values = ["happy", "ok", "sad"]
506585
507586The `remove_enum` action will remove an existing [enum type](https://www.postgresql.org/docs/current/datatype-enum.html). Make sure all usages of the enum has been removed before running the migration. The enum will only be removed once the migration is completed.
508587
509−*Example: remove the `mood` enum type*
588+_Example: remove the `mood` enum type_
510589
511590```toml
512591[[actions]]
@@ -514,61 +593,178 @@ type = "remove_enum"
514593enum = "mood"
515594```
516595
596+### Custom
597+
598+The `custom` action lets you create a migration which runs custom SQL. It should be used with great care as it provides no guarantees of zero-downtime and will simply run whatever SQL is provided. Use other actions whenever possible as they are explicitly designed for zero downtime.
599+
600+There are three optional settings available which all accept SQL queries. All queries need to be idempotent, for example by using `IF NOT EXISTS` wherever available.
601+
602+- `start`: run when a migration is started using `reshape migration start`
603+- `complete`: run when a migration is completed using `reshape migration complete`
604+- `abort`: run when a migration is aborted using `reshape migration abort`
605+
606+_Example: enable PostGIS and pg_stat_statements extensions_
607+
608+```toml
609+[[actions]]
610+type = "custom"
611+
612+start = """
613+ CREATE EXTENSION IF NOT EXISTS postgis;
614+ CREATE EXTENSION IF NOT EXISTS pg_stat_statements;
615+"""
616+
617+abort = """
618+ DROP EXTENSION IF EXISTS postgis;
619+ DROP EXTENSION IF EXISTS pg_stat_statements;
620+"""
621+```
622+
623+### Complex changes across tables
624+
625+The `up` and `down` options available when creating tables, adding columns and removing columns can also perform more complex changes that span tables.
626+
627+_Example: move `email` column from `users` to `profiles` table_
628+
629+```toml
630+[[actions]]
631+type = "add_column"
632+table = "profiles"
633+
634+ [actions.column]
635+ name = "email"
636+ type = "TEXT"
637+ nullable = false
638+
639+ # When `users` is updated in the old schema, we write the email value to `profiles`
640+ [actions.up]
641+ table = "users"
642+ value = "users.email"
643+ where = "profiles.user_id = users.id"
644+
645+[[actions]]
646+type = "remove_column"
647+table = "users"
648+column = "email"
649+
650+ # When `profiles` is changed in the new schema, we write the email address back to the removed column
651+ [actions.down]
652+ table = "profiles"
653+ value = "profiles.email"
654+ where = "users.id = profiles.user_id"
655+```
656+
657+_Example: turn a 1:N relationship between `users` and `accounts` into N:M and change the format of the associated `role`_
658+
659+```toml
660+# Add `user_account_connections` as a junction table
661+[[actions]]
662+type = "create_table"
663+name = "user_account_connections"
664+primary_key = ["account_id", "user_id"]
665+
666+ [[actions.columns]]
667+ name = "account_id"
668+ type = "INTEGER"
669+
670+ [[actions.columns]]
671+ name = "user_id"
672+ type = "INTEGER"
673+
674+ # `role` is currently stored directly on the `users` table but is part of the relationship
675+ [[actions.columns]]
676+ name = "role"
677+ type = "TEXT"
678+ nullable = false
679+
680+ # Backfill the new table from `users` and uppercase the `role`
681+ [actions.up]
682+ table = "users"
683+ values = { user_id = "id", account_id = "account_id", role = "UPPER(account_role)" }
684+ where = "user_account_connections.user_id = users.id"
685+
686+[[actions]]
687+type = "remove_column"
688+table = "users"
689+column = "account_id"
690+
691+ # When `user_account_connections` is updated, we write the `account_id` back to `users`
692+ [actions.down]
693+ table = "user_account_connections"
694+ value = "user_account_connections.account_id"
695+ where = "users.id = user_account_connections.user_id"
696+
697+[[actions]]
698+type = "remove_column"
699+table = "users"
700+column = "account_role"
701+
702+ # When `user_account_connections` is updated, we write the lowercase role back to `users`
703+ [actions.down]
704+ table = "user_account_connections"
705+ value = "LOWER(user_account_connections.role)"
706+ where = "users.id = user_account_connections.user_id"
707+```
708+
517709## Commands and options
518710
519−### `reshape migrate`
711+### `reshape migration start`
520712
521−Starts a new migration, applying all migrations under `migrations/` that haven't yet been applied. After the command has completed, both the old and new schema will be usable at the same time. When you have rolled out the new version of your application which uses the new schema, you should run `reshape complete`.
713+Starts a new migration, applying all migrations under `migrations/` that haven't yet been applied. After the command has completed, both the old and new schema will be usable at the same time. When you have rolled out the new version of your application which uses the new schema, you should run `reshape migration complete`.
522714
523715#### Options
524716
525−*See also [Connection options](#connection-options)*
717+_See also [Connection options](#connection-options)_
526718
527−| Option | Default | Description |
528−| ------ | ------- | ----------- |
529−| `--complete`, `-c` | `false` | Automatically complete migration after applying it. |
530−| `--dirs` | `migrations/` | Directories to search for migration files. Multiple directories can be specified using `--dirs dir1 dir2 dir3`. |
719+| Option | Default | Description |
720+| ------------------ | ------------- | --------------------------------------------------------------------------------------------------------------- |
721+| `--complete`, `-c` | `false` | Automatically complete migration after applying it. |
722+| `--dirs` | `migrations/` | Directories to search for migration files. Multiple directories can be specified using `--dirs dir1 dir2 dir3`. |
531723
532−### `reshape complete`
724+### `reshape migration complete`
533725
534−Completes migrations previously started with `reshape complete`.
726+Completes migrations previously started with `reshape migration complete`.
535727
536728#### Options
537729
538730See [Connection options](#connection-options)
539731
540−### `reshape abort`
732+### `reshape migration abort`
541733
542−Aborts any migrations which haven't yet been completed.
734+Aborts any migrations which haven't yet been completed.
543735
544736#### Options
545737
546738See [Connection options](#connection-options)
547739
548−### `reshape generate-schema-query`
740+### `reshape schema-query`
549741
550742Generates the SQL query you need to run in your application before using the database. This command does not require a database connection. Instead it will generate the query based on the latest migration in the `migrations/` directory (or the directories specified by `--dirs`).
551743
744+If your application is written in Rust, we recommend using the [Rust helper library](https://github.com/fabianlindfors/reshape-helper/) instead.
745+
552746The query should look something like `SET search_path TO migration_1_initial_migration`.
553747
554748#### Options
555749
556−| Option | Default | Description |
557−| ------ | ------- | ----------- |
750+| Option | Default | Description |
751+| -------- | ------------- | --------------------------------------------------------------------------------------------------------------- |
558752| `--dirs` | `migrations/` | Directories to search for migration files. Multiple directories can be specified using `--dirs dir1 dir2 dir3`. |
559753
560754### Connection options
561755
562−The options below can be used with all commands that communicate with Postgres. Use either a connection URL or specify each connection option individually.
756+The options below can be used with all commands that communicate with Postgres. Use either a [connection URL](https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNSTRING) or specify each connection option individually.
757+
758+All options can also be set using environment variables instead of flags. If a `.env` file exists, then variables will be automatically loaded from there.
563759
564−| Option | Default | Description |
565−| ------ | ------- | ----------- |
566−| `--url` | | URI to connect to your Postgres database.<br>Can also be provided with the environment variable `DATABASE_URL`. |
567−| `--host` | `localhost` | Hostname to use when connecting to Postgres |
568−| `--port` | `5432` | Port which Postgres is listening on |
569−| `--database` | `postgres` | Database name |
570−| `--username` | `postgres` | Postgres username |
571−| `--password` | `postgres` | Postgres password |
760+| Option | Default | Environment variable | Description |
761+| ------------ | ----------- | -------------------- | ------------------------------------------- |
762+| `--url` | | `DB_URL` | URL to your Postgres database |
763+| `--host` | `localhost` | `DB_HOST` | Hostname to use when connecting to Postgres |
764+| `--port` | `5432` | `DB_PORT` | Port which Postgres is listening on |
765+| `--database` | `postgres` | `DB_NAME` | Database name |
766+| `--username` | `postgres` | `DB_USERNAME` | Postgres username |
767+| `--password` | `postgres` | `DB_PASSWORD` | Postgres password |
572768
573769## License
574770