Show which dbms support unique index on text columns with variable length

create-table-with-index.sql

CREATE TABLE test (
    test text UNIQUE,
    combined_key_part1 text,
    combined_key_part2 text,

    CONSTRAINT combined_key_unique UNIQUE (combined_key_part1, combined_key_part2)
);

docker-compose.yml

version: "3"
services:
  mariadb:
    image: mariadb:10.5
    environment:
      - MYSQL_DATABASE=db
      - MYSQL_ROOT_PASSWORD=password
    volumes:
      - ./create-table-with-index.sql:/docker-entrypoint-initdb.d/create-table-with-index.sql
    ports:
    - "3306:3306"
  mysql:
    image: mysql:8.0.23
    environment:
      - MYSQL_DATABASE=db
      - MYSQL_ROOT_PASSWORD=password
    volumes:
      - ./create-table-with-index.sql:/docker-entrypoint-initdb.d/create-table-with-index.sql
    ports:
      - "3307:3306"
  postgres:
    image: library/postgres:13.2
    environment:
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=postgres
      - POSTGRES_DB=test
    volumes:
      - ./create-table-with-index.sql:/docker-entrypoint-initdb.d/create-table-with-index.sql
    ports:
      - "5432:5432"

mariadb and postgres allow unique index on text columns, mysql does not

Great test! 👍