Delta Lake Patterns Library: Delta Lake Best Practices

Delta Lake Best Practices A practical guide to Delta Lake patterns, optimizations, and operational strategies for Databricks. 1. Merge Optimization Choose the Right Merge Strategy Pattern Use When Performance SCD1 (Overwrite) You only need the latest value Fast — simple update + insert SCD2 (History) Full audit trail required Moderate — requires hash comparison Upsert General insert-or-update Fast — standard MERGE Delete+Insert Full partition refresh Very fast — avoids row-level matching Conditional Only update if source is newer Moderate — adds condition evaluation Merge Performance Tips Filter source data before merge — only bring records that might match Use partition pruning — add partition columns to merge condition Avoid wide merges — only include columns you actually need to update Pre-sort source data on merge keys when possible Monitor small files — frequent merges create many small files Merge with Delta Table API vs SQL The DeltaTable Python API and SQL MERGE INTO produce id