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Fizz is a common DSL for migrating databases. It tries to be as database-agnostic as possible. This is the default language used by Pop to define database migrations.

Create a Table

create_table("users") {
  t.Column("email", "string", {})
  t.Column("twitter_handle", "string", {"size": 50})
  t.Column("age", "integer", {"default": 0})
  t.Column("admin", "bool", {"default": false})
  t.Column("company_id", "uuid", {"default_raw": "uuid_generate_v1()"})
  t.Column("bio", "text", {"null": true})
  t.Column("joined_at", "timestamp", {})

create_table("todos") {
  t.Column("user_id", "integer", {})
  t.Column("title", "string", {"size": 100})
  t.Column("details", "text", {"null": true})
  t.ForeignKey("user_id", {"users": ["id"]}, {"on_delete": "cascade"})

The id column doesn’t have to be an integer. For instance, you can use an UUID type instead:

create_table("users") {
  t.Column("id", "uuid", {primary: true})
  // ...

By default, fizz will generate two timestamp columns: created_at and updated_at.

The t.Column method takes the following arguments: name of the column, the type of the field, and finally the last argument is any options you want to set on that column.

“Common” Types:

  • string
  • text
  • timestamp, time, datetime
  • integer
  • bool
  • uuid

Any other type passed will be passed straight through to the underlying database.

For example for PostgreSQL you could pass jsonb and it will be supported, however, SQLite will yell very loudly at you if you do the same thing!

Supported Options:

Option Description Example
primary Whether the column is the primary key. To have a composite key look below {"primary": true}
size The size of the column. The default value for a string column is 255 (or 191 for MariaDB) {"size": 50}
scale, precision The scale and the precision for a float column {"scale": 4, "precision": 2}
null By default columns are not allowed to be null {"null": true}
default The default value you want for this column. By default this is null {"default": 0} {"default": false} {"default": "foo"}
default_raw The default value defined as a database function {"default_raw": "uuid_generate_v1()"}
after (MySQL Only) Add a column after another column in the table {"after": "created_at"}
first (MySQL Only) Add a column to the first position in the table {"first": true}

Disable Auto Timestamps

create_table("users") {
  t.Column("id", "uuid", {primary: true})
  // ...
  // Disable auto-creation of created_at and updated_at columns


create_table("users", {timestamps: false}) {
  t.Column("id", "uuid", {primary: true})
  // ...

Drop a Table


Rename a Table

rename_table("old_table_name", "new_table_name")

Add a Column

add_column("table_name", "column_name", "string", {})

See above for more details on column types and options.

Alter a column

change_column("table_name", "column_name", "string", {})

Rename a Column

rename_column("table_name", "old_column_name", "new_column_name")

Drop a Column

drop_column("table_name", "column_name")

Composite Primary Keys

t.PrimaryKey("column_1", "column_2")

Please note that the t.PrimaryKey statement MUST be after the columns definitions.

Add an Index

Supported Options:

  • name - This defaults to table_name_column_name_idx
  • unique

Simple Index:

add_index("table_name", "column_name", {})

Multi-Column Index:

add_index("table_name", ["column_1", "column_2"], {})

Unique Index:

add_index("table_name", "column_name", {"unique": true})

Index Names:

add_index("table_name", "column_name", {}) # name => table_name_column_name_idx
add_index("table_name", "column_name", {"name": "custom_index_name"})

Rename an Index

rename_index("table_name", "old_index_name", "new_index_name")

Drop an Index

drop_index("table_name", "index_name")

Add a Foreign Key

add_foreign_key("table_name", "field", {"ref_table_name": ["ref_column"]}, {
    "name": "optional_fk_name",
    "on_delete": "action",
    "on_update": "action",

Supported Options

  • name - This defaults to table_name_ref_table_name_ref_column_name_fk
  • on_delete - CASCADE, SET NULL, …
  • on_update
Note: on_update and on_delete are not supported on CockroachDB yet.

Drop a Foreign Key

drop_foreign_key("table_name", "fk_name", {"if_exists": true})

Supported Options

  • if_exists - Adds IF EXISTS condition


sql("select * from users;")

Execute an External Command

Sometimes during a migration you need to shell out to an external command.

exec("echo hello")