Start with a few representative files and inspect column types before building a larger query. Keep the source files immutable and save useful SQL alongside the project. Benchmark a realistic join or aggregation on your own hardware, because data layout and intermediate results can matter more than raw input size.
This is best suited to local SQL analysis of analytical files. Before committing a larger project, account for these trade-offs: not a replacement for every transactional server; large workloads still need memory and storage planning.
