Issue Description

The RDBMS schema builder ignores changes in column collation when running schema sync or when generating migrations.

For example, TypeORM may have previously generated a PostgreSQL column of type character varying COLLATE "default". I want to change the collation on the column, so I add the following decorator:

@Column({ collation: 'en-US-x-icu' })

Expected Behavior

Running typeorm schema:sync should update the collation of the column to "en-US-x-icu".

Running typeorm migration:generate should generate a migration with the query ALTER TABLE ... ALTER COLUMN ... SET DATA TYPE ... COLLATE "en-US-x-icu" as expected by PostgreSQL, or correspondingly for other DBMS's.

Actual Behavior

Running typeorm schema:sync does not change the collation of any existing columns.

Running typeorm migration:generate shows "No changes in database schema were found - cannot generate a migration."

I can still set the correct collation by running typeorm schema:drop and then typeorm schema:sync, but this obviously deletes all data, which is not always desirable.

Steps to Reproduce

1. Create an entity:

import { Entity, Column } from 'typeorm';

@Entity()
export class Foo {
  @Column()
  name: string;
}

2. Run typeorm schema:sync.
3. There should now be a column named "foo"."name" with the default collation.
4. Change the entity:

import { Entity, Column } from 'typeorm';

@Entity()
export class Foo {
  @Column({ collation: 'en-US-x-icu' })
  name: string;
}

5. Run typeorm schema:sync again.
6. Observe that the collation in the database has not been updated.

My Environment

Additional Context

Relevant Database Driver(s)

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• ✖️ No, I don’t have the time and I’m okay to wait for the community / maintainers to resolve this issue.