@@ -2,54 +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− - [Columns](#columns)
26− - [Add column](#add-column)
27− - [Alter column](#alter-column)
28− - [Remove column](#remove-column)
29− - [Indices](#indices)
30− - [Add index](#add-index)
31− - [Remove index](#remove-index)
32− - [Enums](#enums)
33− - [Create enum](#create-enum)
34− - [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)
3538- [Commands and options](#commands-and-options)
36− - [`reshape migrate`](#reshape-migrate)
37− - [`reshape complete`](#reshape-complete)
38− - [`reshape abort`](#reshape-abort)
39− - [`reshape generate-schema-query`](#reshape-generate-schema-query)
40− - [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)
4144- [License](#license)
4245
43−
4446## How it works
4547
4648Reshape 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:
4749
48−1. **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.
49512. **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.
50−3. **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.
5153
52−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.
5355
5456## Getting started
5557
@@ -61,7 +63,7 @@ Binaries are available for macOS and Linux under [Releases](https://github.com/f
6163
6264#### Cargo
6365
64−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):
6567
6668```shell
6769cargo install reshape
@@ -69,10 +71,10 @@ cargo install reshape
6971
7072#### Docker
7173
72−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).
7375
7476```shell
75−docker run -v $(pwd):/usr/share/app fabianlindfors/reshape reshape migrate
77+docker run -v $(pwd):/usr/share/app fabianlindfors/reshape reshape migration start
7678```
7779
7880### Creating your first migration
@@ -101,9 +103,14 @@ This is the equivalent of running `CREATE TABLE users (id INTEGER GENERATED ALWA
101103
102104### Preparing your application
103105
104−Reshape relies on your application using a specific schema. When establishing the connection to Postgres in your application, you need to run a query to select the most recent schema. This query can be generated using: `reshape generate-schema-query`.
106+Reshape relies on your application using a specific schema. When establishing the connection to Postgres in your application, you need to run a query to select the most recent schema. The simplest way to do this is to use one of the helper libraries:
105107
106−To pass it along to your application, you can for example use an environment variable in your run script: `RESHAPE_SCHEMA_QUERY=$(reshape generate-schema-query)`. Then in your application:
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)
112+
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:
107114
108115```python
109116# Example for Python
@@ -116,16 +123,16 @@ db.execute(reshape_schema_query)
116123To create your new `users` table, run:
117124
118125```bash
119−reshape migrate
126+reshape migration start --complete
120127```
121128
122−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.
123130
124131If 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.
125132
126133### Using during development
127134
128−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`.
129136
130137## Writing migrations
131138
@@ -160,9 +167,9 @@ Every action has a `type`. The supported types are detailed below.
160167
161168#### Create table
162169
163−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.
164171
165−*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_
166173
167174```toml
168175[[actions]]
@@ -180,13 +187,13 @@ primary_key = ["id"]
180187 type = "TEXT"
181188
182189 # Columns default to nullable
183− nullable = false
190+ nullable = false
184191
185192 # default can be any valid SQL value, in this case a string literal
186− default = "'PLACEHOLDER'"
193+ default = "'PLACEHOLDER'"
187194```
188195
189−*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_
190197
191198```toml
192199[[actions]]
@@ -219,11 +226,34 @@ primary_key = ["id"]
219226 referenced_columns = ["id"]
220227```
221228
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+
222252#### Rename table
223253
224254The `rename_table` action will change the name of an existing table.
225255
226−*Example: change name of `users` table to `customers`*
256+_Example: change name of `users` table to `customers`_
227257
228258```toml
229259[[actions]]
@@ -236,7 +266,7 @@ new_name = "customers"
236266
237267The `remove_table` action will remove an existing table.
238268
239−*Example: remove `users` table*
269+_Example: remove `users` table_
240270
241271```toml
242272[[actions]]
@@ -248,7 +278,7 @@ table = "users"
248278
249279The `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.
250280
251−*Example: create foreign key from `items` to `users` table*
281+_Example: create foreign key from `items` to `users` table_
252282
253283```toml
254284[[actions]]
@@ -261,13 +291,26 @@ table = "items"
261291 referenced_columns = ["id"]
262292```
263293
294+#### Remove foreign key
295+
296+The `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.
297+
298+_Example: remove foreign key `items_user_id_fkey` from `users` table_
299+
300+```toml
301+[[actions]]
302+type = "remove_foreign_key"
303+table = "items"
304+foreign_key = "items_user_id_fkey"
305+```
306+
264307### Columns
265308
266309#### Add column
267310
268−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)).
269312
270−*Example: add a new column `reference` to table `products`*
313+_Example: add a new column `reference` to table `products`_
271314
272315```toml
273316[[actions]]
@@ -281,7 +324,7 @@ table = "products"
281324 default = "10"
282325```
283326
284−*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`_
285328
286329```toml
287330[[actions]]
@@ -317,14 +360,48 @@ column = "name"
317360down = "first_name || ' ' || last_name"
318361```
319362
363+_Example: extract nested value from unstructured JSON `data` column to new `name` column_
364+
365+```toml
366+[[actions]]
367+type = "add_column"
368+table = "users"
369+
370+# #>> '{}' converts the JSON string value to TEXT
371+up = "data['path']['to']['value'] #>> '{}'"
372+
373+ [actions.column]
374+ name = "name"
375+ type = "TEXT"
376+```
377+
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+```
320397
321398#### Alter column
322399
323400The `alter_column` action enables many different changes to an existing column, for example renaming, changing type and changing existing values.
324401
325−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.
326403
327−*Example: rename `last_name` column on `users` table to `family_name`*
404+_Example: rename `last_name` column on `users` table to `family_name`_
328405
329406```toml
330407[[actions]]
@@ -336,7 +413,7 @@ column = "last_name"
336413 name = "family_name"
337414```
338415
339−*Example: change the type of `reference` column from `INTEGER` to `TEXT`*
416+_Example: change the type of `reference` column from `INTEGER` to `TEXT`_
340417
341418```toml
342419[[actions]]
@@ -351,7 +428,7 @@ down = "CAST(reference AS INTEGER)" # Converts from text value to integer
351428 type = "TEXT" # Previous type was 'INTEGER'
352429```
353430
354−*Example: increment all values of an `index` column by one*
431+_Example: increment all values of an `index` column by one_
355432
356433```toml
357434[[actions]]
@@ -366,7 +443,22 @@ down = "index - 1" # Decrement to revert for old schema
366443 name = "index"
367444```
368445
369−*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_
370462
371463```toml
372464[[actions]]
@@ -380,11 +472,11 @@ column = "created_at"
380472
381473#### Remove column
382474
383−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.
384476
385477Any indices that cover the column will be removed.
386478
387−*Example: remove column `name` from table `users`*
479+_Example: remove column `name` from table `users`_
388480
389481```toml
390482[[actions]]
@@ -396,18 +488,34 @@ column = "name"
396488down = "'N/A'"
397489```
398490
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+
399507### Indices
400508
401509#### Add index
402510
403511The `add_index` action will add a new index to an existing table.
404512
405−*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_
406514
407515```toml
408516[[actions]]
409517type = "create_table"
410−table = "users"
518+name = "users"
411519primary_key = "id"
412520
413521 [[actions.columns]]
@@ -431,7 +539,7 @@ table = "users"
431539 unique = true
432540```
433541
434−*Example: add GIN index to `data` column on `products` table*
542+_Example: add GIN index to `data` column on `products` table_
435543
436544```toml
437545[[actions]]
@@ -450,7 +558,7 @@ table = "products"
450558
451559The `remove_index` action will remove an existing index. The index won't actually be removed until the migration is completed.
452560
453−*Example: remove the `name_idx` index*
561+_Example: remove the `name_idx` index_
454562
455563```toml
456564[[actions]]
@@ -464,7 +572,7 @@ index = "name_idx"
464572
465573The `create_enum` action will create a new [enum type](https://www.postgresql.org/docs/current/datatype-enum.html) with the specified values.
466574
467−*Example: add a new `mood` enum type with three possible values*
575+_Example: add a new `mood` enum type with three possible values_
468576
469577```toml
470578[[actions]]
@@ -477,7 +585,7 @@ values = ["happy", "ok", "sad"]
477585
478586The `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.
479587
480−*Example: remove the `mood` enum type*
588+_Example: remove the `mood` enum type_
481589
482590```toml
483591[[actions]]
@@ -485,61 +593,178 @@ type = "remove_enum"
485593enum = "mood"
486594```
487595
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+
488709## Commands and options
489710
490−### `reshape migrate`
711+### `reshape migration start`
491712
492−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`.
493714
494715#### Options
495716
496−*See also [Connection options](#connection-options)*
717+_See also [Connection options](#connection-options)_
497718
498−| Option | Default | Description |
499−| ------ | ------- | ----------- |
500−| `--complete`, `-c` | `false` | Automatically complete migration after applying it. |
501−| `--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`. |
502723
503−### `reshape complete`
724+### `reshape migration complete`
504725
505−Completes migrations previously started with `reshape complete`.
726+Completes migrations previously started with `reshape migration complete`.
506727
507728#### Options
508729
509730See [Connection options](#connection-options)
510731
511−### `reshape abort`
732+### `reshape migration abort`
512733
513−Aborts any migrations which haven't yet been completed.
734+Aborts any migrations which haven't yet been completed.
514735
515736#### Options
516737
517738See [Connection options](#connection-options)
518739
519−### `reshape generate-schema-query`
740+### `reshape schema-query`
520741
521742Generates 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`).
522743
744+If your application is written in Rust, we recommend using the [Rust helper library](https://github.com/fabianlindfors/reshape-helper/) instead.
745+
523746The query should look something like `SET search_path TO migration_1_initial_migration`.
524747
525748#### Options
526749
527−| Option | Default | Description |
528−| ------ | ------- | ----------- |
750+| Option | Default | Description |
751+| -------- | ------------- | --------------------------------------------------------------------------------------------------------------- |
529752| `--dirs` | `migrations/` | Directories to search for migration files. Multiple directories can be specified using `--dirs dir1 dir2 dir3`. |
530753
531754### Connection options
532755
533−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.
534759
535−| Option | Default | Description |
536−| ------ | ------- | ----------- |
537−| `--url` | | URI to connect to your Postgres database.<br>Can also be provided with the environment variable `DATABASE_URL`. |
538−| `--host` | `localhost` | Hostname to use when connecting to Postgres |
539−| `--port` | `5432` | Port which Postgres is listening on |
540−| `--database` | `postgres` | Database name |
541−| `--username` | `postgres` | Postgres username |
542−| `--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 |
543768
544769## License
545770