1. Database Migration advanced

    A billing platform is extracting services from a shared database. Should the code be split first or the data?

    2 min answer chargebeedecompositiondatabaseownership
  2. Database Migration advanced

    A product must move its primary data store while remaining live, with no acceptable data loss. What is the migration sequence, and where do these go wrong?

    2 min answer database-migrationdual-writeverificationcutover
  3. Database Migration beginner Multiple choice

    A team plans to move 2.5 TB to a new database by taking the application offline at 22:00 on Saturday, restoring a backup into the new store, and switching over by 08:00 Sunday. The data copies fine in a test at one tenth the volume. Why does this plan usually fail before it is executed?

    3 min answer cutoverrestorerollbackmaintenance window
  4. Database Migration advanced

    An online schema change is needed on a billion-row MySQL table with zero downtime. Compare trigger-based, binlog-based and native approaches, and describe how the change is gated and reverted.

    3 min answer schema-changegh-ostpt-online-schema-changemysql
  5. Database Migration advanced

    Notion sharded its Postgres data into 480 logical shards across 32 physical databases in 2021 and then in 2023 spread the same 480 logical shards across 96 databases, with no change to the routing logic. What did the 2021 decision buy, what did the 2023 move still cost, and where would copying the number be a mistake?

    3 min answer notionpostgresshardingresharding
  6. Database Migration advanced

    Walk through migrating a live database to a different engine with no downtime. Where does reversibility end?

    2 min answer migrationverificationshadow-readsreversibility