@@ -2,54 +2,54 @@
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−
75Reshape 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/).
86
97Designed for Postgres 12 and later.
108
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)
36− - [Custom](#custom)
37− - [Complex changes across tables](#complex-changes-across-tables)
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)
3837- [Commands and options](#commands-and-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)
38+ - [`reshape migration start`](#reshape-migration-start)
39+ - [`reshape migration complete`](#reshape-migration-complete)
40+ - [`reshape migration abort`](#reshape-migration-abort)
41+ - [`reshape schema-query`](#reshape-schema-query)
42+ - [Connection options](#connection-options)
4443- [License](#license)
4544
45+
4646## How it works
4747
4848Reshape 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:
4949
50501. **Start migration** (`reshape migration start`): Sets up views and triggers to ensure both the new and old schema are usable at the same time.
51512. **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.
52−3. **Complete migration** (`reshape migration 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.
5353
5454If the application deployment fails, you should run `reshape migration abort` which will roll back any changes made by `reshape migration start` without losing data.
5555
@@ -71,7 +71,7 @@ cargo install reshape
7171
7272#### Docker
7373
74−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).
7575
7676```shell
7777docker run -v $(pwd):/usr/share/app fabianlindfors/reshape reshape migration start
@@ -108,7 +108,6 @@ Reshape relies on your application using a specific schema. When establishing th
108108- [Rust](https://github.com/fabianlindfors/reshape-helper)
109109- [Ruby (and Rails)](https://github.com/fabianlindfors/reshape-ruby)
110110- [Python (and Django)](https://github.com/fabianlindfors/reshape-python)
111−- [Go](https://github.com/leourbina/reshape-helper)
112111
113112If your application is not using one of the languages with an available helper library, you can instead generate the query with the command: `reshape schema-query`. To pass it along to your application, you can for example use an environment variable in your run script: `RESHAPE_SCHEMA_QUERY=$(reshape schema-query)`. Then in your application:
114113
@@ -167,9 +166,9 @@ Every action has a `type`. The supported types are detailed below.
167166
168167#### Create table
169168
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.
169+The `create_table` action will create a new table with the specified columns, indices and constraints.
171170
172−_Example: create a `customers` table with a few columns and a primary key_
171+*Example: create a `customers` table with a few columns and a primary key*
173172
174173```toml
175174[[actions]]
@@ -187,13 +186,13 @@ primary_key = ["id"]
187186 type = "TEXT"
188187
189188 # Columns default to nullable
190− nullable = false
189+ nullable = false
191190
192191 # default can be any valid SQL value, in this case a string literal
193− default = "'PLACEHOLDER'"
192+ default = "'PLACEHOLDER'"
194193```
195194
196−_Example: create `users` and `items` tables with a foreign key between them_
195+*Example: create `users` and `items` tables with a foreign key between them*
197196
198197```toml
199198[[actions]]
@@ -226,34 +225,11 @@ primary_key = ["id"]
226225 referenced_columns = ["id"]
227226```
228227
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−
252228#### Rename table
253229
254230The `rename_table` action will change the name of an existing table.
255231
256−_Example: change name of `users` table to `customers`_
232+*Example: change name of `users` table to `customers`*
257233
258234```toml
259235[[actions]]
@@ -266,7 +242,7 @@ new_name = "customers"
266242
267243The `remove_table` action will remove an existing table.
268244
269−_Example: remove `users` table_
245+*Example: remove `users` table*
270246
271247```toml
272248[[actions]]
@@ -278,7 +254,7 @@ table = "users"
278254
279255The `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.
280256
281−_Example: create foreign key from `items` to `users` table_
257+*Example: create foreign key from `items` to `users` table*
282258
283259```toml
284260[[actions]]
@@ -295,7 +271,7 @@ table = "items"
295271
296272The `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.
297273
298−_Example: remove foreign key `items_user_id_fkey` from `users` table_
274+*Example: remove foreign key `items_user_id_fkey` from `users` table*
299275
300276```toml
301277[[actions]]
@@ -308,9 +284,9 @@ foreign_key = "items_user_id_fkey"
308284
309285#### Add column
310286
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)).
287+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.
312288
313−_Example: add a new column `reference` to table `products`_
289+*Example: add a new column `reference` to table `products`*
314290
315291```toml
316292[[actions]]
@@ -324,7 +300,7 @@ table = "products"
324300 default = "10"
325301```
326302
327−_Example: replace an existing `name` column with two new columns, `first_name` and `last_name`_
303+*Example: replace an existing `name` column with two new columns, `first_name` and `last_name`*
328304
329305```toml
330306[[actions]]
@@ -360,7 +336,7 @@ column = "name"
360336down = "first_name || ' ' || last_name"
361337```
362338
363−_Example: extract nested value from unstructured JSON `data` column to new `name` column_
339+*Example: extract nested value from unstructured JSON `data` column to new `name` column*
364340
365341```toml
366342[[actions]]
@@ -375,25 +351,6 @@ up = "data['path']['to']['value'] #>> '{}'"
375351 type = "TEXT"
376352```
377353
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−```
397354
398355#### Alter column
399356
@@ -401,7 +358,7 @@ The `alter_column` action enables many different changes to an existing column,
401358
402359When 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.
403360
404−_Example: rename `last_name` column on `users` table to `family_name`_
361+*Example: rename `last_name` column on `users` table to `family_name`*
405362
406363```toml
407364[[actions]]
@@ -413,7 +370,7 @@ column = "last_name"
413370 name = "family_name"
414371```
415372
416−_Example: change the type of `reference` column from `INTEGER` to `TEXT`_
373+*Example: change the type of `reference` column from `INTEGER` to `TEXT`*
417374
418375```toml
419376[[actions]]
@@ -428,7 +385,7 @@ down = "CAST(reference AS INTEGER)" # Converts from text value to integer
428385 type = "TEXT" # Previous type was 'INTEGER'
429386```
430387
431−_Example: increment all values of an `index` column by one_
388+*Example: increment all values of an `index` column by one*
432389
433390```toml
434391[[actions]]
@@ -443,7 +400,7 @@ down = "index - 1" # Decrement to revert for old schema
443400 name = "index"
444401```
445402
446−_Example: make `name` column not nullable_
403+*Example: make `name` column not nullable*
447404
448405```toml
449406[[actions]]
@@ -458,7 +415,7 @@ up = "COALESCE(name, 'N/A')"
458415 nullable = false
459416```
460417
461−_Example: change default value of `created_at` column to current time_
418+*Example: change default value of `created_at` column to current time*
462419
463420```toml
464421[[actions]]
@@ -472,11 +429,11 @@ column = "created_at"
472429
473430#### Remove column
474431
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.
432+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.
476433
477434Any indices that cover the column will be removed.
478435
479−_Example: remove column `name` from table `users`_
436+*Example: remove column `name` from table `users`*
480437
481438```toml
482439[[actions]]
@@ -488,29 +445,13 @@ column = "name"
488445down = "'N/A'"
489446```
490447
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−
507448### Indices
508449
509450#### Add index
510451
511452The `add_index` action will add a new index to an existing table.
512453
513−_Example: create a `users` table with a unique index on the `name` column_
454+*Example: create a `users` table with a unique index on the `name` column*
514455
515456```toml
516457[[actions]]
@@ -539,7 +480,7 @@ table = "users"
539480 unique = true
540481```
541482
542−_Example: add GIN index to `data` column on `products` table_
483+*Example: add GIN index to `data` column on `products` table*
543484
544485```toml
545486[[actions]]
@@ -558,7 +499,7 @@ table = "products"
558499
559500The `remove_index` action will remove an existing index. The index won't actually be removed until the migration is completed.
560501
561−_Example: remove the `name_idx` index_
502+*Example: remove the `name_idx` index*
562503
563504```toml
564505[[actions]]
@@ -572,7 +513,7 @@ index = "name_idx"
572513
573514The `create_enum` action will create a new [enum type](https://www.postgresql.org/docs/current/datatype-enum.html) with the specified values.
574515
575−_Example: add a new `mood` enum type with three possible values_
516+*Example: add a new `mood` enum type with three possible values*
576517
577518```toml
578519[[actions]]
@@ -585,7 +526,7 @@ values = ["happy", "ok", "sad"]
585526
586527The `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.
587528
588−_Example: remove the `mood` enum type_
529+*Example: remove the `mood` enum type*
589530
590531```toml
591532[[actions]]
@@ -603,7 +544,7 @@ There are three optional settings available which all accept SQL queries. All qu
603544- `complete`: run when a migration is completed using `reshape migration complete`
604545- `abort`: run when a migration is aborted using `reshape migration abort`
605546
606−_Example: enable PostGIS and pg_stat_statements extensions_
547+*Example: enable PostGIS and pg_stat_statements extensions*
607548
608549```toml
609550[[actions]]
@@ -620,92 +561,6 @@ abort = """
620561"""
621562```
622563
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−
709564## Commands and options
710565
711566### `reshape migration start`
@@ -714,16 +569,16 @@ Starts a new migration, applying all migrations under `migrations/` that haven't
714569
715570#### Options
716571
717−_See also [Connection options](#connection-options)_
572+*See also [Connection options](#connection-options)*
718573
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`. |
574+| Option | Default | Description |
575+| ------ | ------- | ----------- |
576+| `--complete`, `-c` | `false` | Automatically complete migration after applying it. |
577+| `--dirs` | `migrations/` | Directories to search for migration files. Multiple directories can be specified using `--dirs dir1 dir2 dir3`. |
723578
724579### `reshape migration complete`
725580
726−Completes migrations previously started with `reshape migration complete`.
581+Completes migrations previously started with `reshape migration complete`.
727582
728583#### Options
729584
@@ -731,7 +586,7 @@ See [Connection options](#connection-options)
731586
732587### `reshape migration abort`
733588
734−Aborts any migrations which haven't yet been completed.
589+Aborts any migrations which haven't yet been completed.
735590
736591#### Options
737592
@@ -747,8 +602,8 @@ The query should look something like `SET search_path TO migration_1_initial_mig
747602
748603#### Options
749604
750−| Option | Default | Description |
751−| -------- | ------------- | --------------------------------------------------------------------------------------------------------------- |
605+| Option | Default | Description |
606+| ------ | ------- | ----------- |
752607| `--dirs` | `migrations/` | Directories to search for migration files. Multiple directories can be specified using `--dirs dir1 dir2 dir3`. |
753608
754609### Connection options
@@ -757,14 +612,14 @@ The options below can be used with all commands that communicate with Postgres.
757612
758613All options can also be set using environment variables instead of flags. If a `.env` file exists, then variables will be automatically loaded from there.
759614
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 |
615+| Option | Default | Environment variable | Description |
616+| ------ | ------- | -------------------- | ----------- |
617+| `--url` | | `DB_URL` | URL to your Postgres database |
618+| `--host` | `localhost` | `DB_HOST` | Hostname to use when connecting to Postgres |
619+| `--port` | `5432` | `DB_PORT` | Port which Postgres is listening on |
620+| `--database` | `postgres` | `DB_NAME` | Database name |
621+| `--username` | `postgres` | `DB_USERNAME` | Postgres username |
622+| `--password` | `postgres` | `DB_PASSWORD` | Postgres password |
768623
769624## License
770625