databaseChangeLog:
  - changeSet:
      id: 014-create-chats
      author: krylov
      comment: >
        Таблица чатов. Раньше создавалась Hibernate (ddl-auto: update),
        поэтому changeset идемпотентен: если таблица уже есть — MARK_RAN.
      preConditions:
        onFail: MARK_RAN
        not:
          tableExists:
            tableName: chats
      changes:
        - createTable:
            tableName: chats
            columns:
              - column: { name: id, type: BIGSERIAL, constraints: { primaryKey: true } }
              - column: { name: user_one_id, type: BIGINT, constraints: { nullable: false } }
              - column: { name: user_two_id, type: BIGINT, constraints: { nullable: false } }
              - column: { name: post_id, type: BIGINT }
              - column: { name: created_at, type: TIMESTAMP, constraints: { nullable: false } }
        - addUniqueConstraint:
            tableName: chats
            columnNames: user_one_id, user_two_id
            constraintName: uq_chat_users

  - changeSet:
      id: 014-chats-idx-participants
      author: krylov
      comment: >
        findAllByUserId ищет по (user_one_id = ? OR user_two_id = ?),
        без индексов это full scan по всем чатам.
      preConditions:
        onFail: MARK_RAN
        tableExists:
          tableName: chats
        not:
          indexExists:
            tableName: chats
            indexName: idx_chats_user_one
      changes:
        - createIndex:
            tableName: chats
            indexName: idx_chats_user_one
            columns:
              - column: { name: user_one_id }

  - changeSet:
      id: 014-chats-idx-participants-two
      author: krylov
      preConditions:
        onFail: MARK_RAN
        tableExists:
          tableName: chats
        not:
          indexExists:
            tableName: chats
            indexName: idx_chats_user_two
      changes:
        - createIndex:
            tableName: chats
            indexName: idx_chats_user_two
            columns:
              - column: { name: user_two_id }