Delta Lake use parquet file format, but what is the key difference to standard parquet file storage?
In a nutshell, Delta Lake extends the capabilities of the Parquet file format by providing ACID transactions, schema evolution, metadata management, time travel, and performance optimizations.
ACID and versioning
The standard Parquet file format does not provide built-in transactional capabilities, nor built-in metadata management for tracking changes and versions.
Delta Lake maintains transaction logs and metadata that track changes to the data. This metadata includes information about commits, versions, and schema changes, making it possible to achieve ACID, schema eveolution, data auditting, time travel
Optimization for both read and write
Delta Lake also includes optimizations for performance, such as data skipping and caching, which can improve query performance significantly.
The standard parquet files are efficient for read-heavy workloads, Delta Lake introduces optimizations that enhance both read and write performance.
Streaming
Delta Lake supports streaming writes, allowing ingestion of data in real-time or batch mode while ensuring ACID.
The standard Parquet files are typically written in batch mode.