Squashing database migrations

For convenience, squash_migrations.sh script squashes the migrations, but whoever PRs the result is responsible for verifying that the migrations are squashed and LastSquashedMigrationVersion in db/admin.go is updated correctly, regardless of the result of having run the script.

Each major release of Apache Traffic Control combines database migrations from previous ATC releases into create_tables.sql.

For example, suppose the latest version of Apache Traffic Control is 147.5.8 and contains these migrations:

  • 1_my-migration.up.sql
  • 1_my-migration.down.sql
  • 3_another-migration.up.sql
  • 3_another-migration.down.sql

And suppose the ATC master branch contains these migrations:

  • 1_my-migration.up.sql
  • 1_my-migration.down.sql
  • 3_another-migration.up.sql
  • 3_another-migration.down.sql
  • 4_migration-name.up.sql
  • 4_migration-name.down.sql
  • 9_add-column-to-table.up.sql
  • 9_add-column-to-table.down.sql

  1. In order to prepare database migrations for the next major release, in this case, ATC 148.0.0, migrations 1 and 3 should be collapsed into create_tables.sql and migrations 4 and 9 should remain in traffic_ops/app/db/migrations/.

    • Note that 3 is the migration timestamp of the last up/down migration set. Find the definition for LastSquashedMigrationTimestamp in traffic_ops/app/db/admin.go and change it to 3.
    • After migrations from ATC 147.5.8 have been collapsed, the first migration version will be 4. Find the definition for FirstMigrationTimestamp in traffic_ops/app/db/admin.go and change it to 4.

Past PRs that have collapsed the DB migrations: