Assess the complexity, estimate the effort, and identify risks for your database migration - whether moving between engines, cloud providers, or on-premise to cloud.
| Source → Target | SQL Server | PostgreSQL | MySQL | MongoDB | Oracle |
|---|---|---|---|---|---|
| SQL Server | Low | Moderate | Moderate | High | Moderate |
| Oracle | Moderate | Moderate–High | High | Very High | Low |
| MySQL | Moderate | Low–Moderate | Low | High | Moderate |
| PostgreSQL | Moderate | Low | Low–Moderate | High | Moderate |
| MongoDB | High | High | High | Low | High |
| Other | High | High | High | Very High | High |
Complexity ratings assume moderate schema complexity and standard data types. Stored procedures, triggers, and custom types increase complexity significantly. Talk to our migration team
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Complexity depends primarily on schema size, data volume, and how compatible your source and target database systems are - migrating between similar systems is typically straightforward, while cross-platform migrations, for example SQL Server to PostgreSQL, usually require significant schema and query rework. This assessor scores your project against these factors.
For a small-to-mid-sized UK SME database, migrations typically take 2-8 weeks including planning, testing, and cutover, though complex cross-platform migrations with custom application dependencies can take several months. Testing and validation usually take longer than the actual data transfer itself.
The most common causes are underestimating data cleanup needs, undiscovered application dependencies on database-specific features, and insufficient testing time before cutover. Most UK SMEs also underestimate the staff time needed for validation, which is why this assessor weighs schema complexity and compatibility heavily.
It depends on the migration method - a straightforward lift-and-shift typically requires a planned maintenance window of a few hours, while a phased or replication-based migration can reduce downtime to minutes at the cost of a more complex project. Most UK SMEs opt for a scheduled out-of-hours cutover to minimise disruption.
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