Phase 8 introduced native columnar storage and a vectorized execution engine to drastically improve the performance of analytical workloads.
Implemented a high-performance column-oriented data store.
- Binary Column Files: Stores data in contiguous binary files on disk, one per column.
- Batch Read/Write: Optimized I/O paths for loading and retrieving large blocks of data efficiently.
- Schema-Defined Layout: Automatically organizes data based on the table's schema definition.
Developed SIMD-friendly contiguous memory buffers for batch processing.
- ColumnVector & NumericVector: Specialized C++ templates for storing a "vector" of data for a single column.
- VectorBatch: A collection of
ColumnVectorobjects representing a chunk of rows (typically 1024 rows).
Built a batch-at-a-time physical execution model.
- Vectorized Operators: Implemented
Scan,Filter,Project, andAggregateoperators designed for chunk-based execution. - Batch-at-a-Time Interface: Operators pass entire
VectorBatchobjects between themselves, minimizing virtual function call overhead.
Optimized global analytical queries (COUNT, SUM).
- Vectorized Global Aggregate: Aggregates entire batches of data with minimal branching and high cache locality.
- Type-Specific Aggregation: Leverages C++ templates to generate highly efficient aggregation logic for different data types.
- Vectorized execution significantly outperforms the traditional Volcano model for large-scale analytical queries.
- Columnar storage is essential for minimizing I/O overhead when only a subset of columns is accessed.
Successfully verified the end-to-end vectorized pipeline, including columnar data persistence and complex analytical query patterns, through dedicated integration tests.