Indexing the Data Lake for Online Point Queries
Random Access Parquet (RAP) adds an external multimap index that stores key-to-file-location mappings for existing, unmodified Parquet files, collapsing distributed SQL overhead into a single O(1) lookup and parallel ranged reads—enabling sub-second online point queries over exabyte-scale data lakes without data duplication.
Fits the architecture-and-design-guidance lens cleanly. The core reframe is that the bottleneck in data-lake point queries is not storage bandwidth but the chain of dependent metadata reads—BigQuery and friends pay seconds of overhead even for single-row lookups because they weren't built for this access pattern. RAP bypasses that chain entirely with an index that is separate from the data, meaning analytics pipelines continue using the same Parquet files unchanged. The three-tier optimization hierarchy (concentrating key data, reducing bytes per read, reducing read operations) is concrete enough to apply: ZSTD frame resets, column interleaving, and covering indexes with hoisted values are each specific, actionable design decisions. The design is motivated by real cost data (terabytes of data produce gigabytes of index as a rule of thumb). Good for anyone operating an analytics lake who also needs to serve online workloads or AI agents from the same storage.