Tomasz Wielecki

Pre-migration data remediation determines success more than the technical transfer work itself.

Clean data before migration prevents expensive problems in your new platform.

Assertions catch data problems before exploratory results become unreliable input.

Distinguish monotonic ordering from gap-free continuity in SQL assertions.

Matching row counts masks data mismatches that reconciliation queries can catch.

Spot missing references with a simple LEFT JOIN query pattern.

Catch silent type conversions before they corrupt downstream data.