Description

Whether to create placeholders in the generated migration script. If set to true, Flyway will attempt to insert placeholders into the script.

These placeholders can then be used when you deploy the script using Flyway placeholders replacement mechanism. This results in an abstraction of the generated script away from specific database parameter values (for example the database instance or schema names).

For example, if flyway generate <...> would create the following SQL:

CREATE TABLE dbo.foo (
    id INT NOT NULL,
    name VARCHAR(255) NOT NULL
);

flyway generate -generate.usePlaceholders=true -placeholders.schema=dbo <...> would create:

CREATE TABLE ${schema}.foo (
    id INT NOT NULL,
    name VARCHAR(255) NOT NULL
);

Please note - this is doing a text pattern match for the string "dbo" and replacing it with the string "${schema}", this is what -placeholders.schema=dbo defines. It isn't aware of SQL syntax or your database !

Evaluation order

Placeholders are evaluated in order of longest value first. This means that if you have these placeholders:

flyway generate -generate.usePlaceholders=true -placeholders.foo=local -placeholders.bar=localhost

Any text matching the string "localhost" will be replaced with the string "${bar}", and then any remaining text matching "local" will be replaced with "${foo}".

Limitations

If multiple placeholders are specified with the same value, Flyway will throw an exception. For example, if you specify -placeholders.schema=dbo -placeholders.x=dbo, Flyway will throw an error.

The reason being that you are asking Flyway to replace the string "dbo" with both "${schema}" and "${x}" which can't be done.

Type

Boolean

Default

false

Usage

Flyway Desktop

This can't be added to a configuration file via Flyway Desktop.

Command-line

./flyway generate -usePlaceholders=true

TOML Configuration File

[flyway.generate]
usePlaceholders = true