S4 Scan - Athena Scan-Cost Reducer

S4 Scan learns from your Athena query history which columns are read and which predicates filter your tables, then rewrites the underlying S3 Parquet into the physical layout those queries want: hot columns first, sorted on the columns you filter by so row-group statistics prune, low-cardinality columns dictionary-encoded, files compacted to an efficient size, and compressed with zstd. Athena and Redshift Spectrum bill per terabyte scanned from S3, so a smaller, better-pruned layout is a direct, recurring bill reduction.

Safety is the core of the product. S4 Scan never overwrites your source data in place: it writes optimized data to a shadow location, verifies that every query returns byte-for-byte identical results (values, nulls, decimal scale, timestamp time zone), and only then swaps the AWS Glue table pointer. One-command rollback restores the original layout at any time; if verification fails the swap is refused. There is no lock-in - output is standard, Athena-readable Parquet using standard codecs.

The dry-run command projects the dollar savings on your real tables before you commit, attributing the reduction honestly across pruning, compression, and compaction. S4 Scan ships as a self-contained AMI that re-optimizes on an EventBridge schedule with no human in the loop, billed per instance per hour through your AWS bill.