Tell about database migrations: how they were performed, how errors were handled during migration?

I usually performed database migrations using tools like Goose or Flyway, which allow managing schema versions and applying changes sequentially.

Migration process:

1. Created migration scripts with schema changes (creating tables, modifying columns, etc.).
2. Tested migrations in a test environment.
3. Applied migrations to staging, checked correctness.
4. Performed migration on production with minimal downtime.

Error handling:

• Used transactions in migrations so that changes are rolled back in case of errors.
• Logged errors and notified the team.
• In critical errors, rolled back the migration and analyzed the problem.
• In complex cases, wrote scripts for manual data correction.

Example of migration from Goose to Go:

package main

import (
    "database/sql"
    "github.com/pressly/goose/v3"
)

func Up(tx *sql.Tx) error {
    _, err := tx.Exec(`ALTER TABLE users ADD COLUMN age INT;`)
    return err
}

func Down(tx *sql.Tx) error {
    _, err := tx.Exec(`ALTER TABLE users DROP COLUMN age;`)
    return err
}

This approach ensures version control and safety of changes.