content-hash-cache-pattern

Cache expensive file processing results by computing a SHA-256 content hash for each file and storing outputs as {hash}.json. This content-hash caching pattern eliminates wasted recomputation across runs for identical files.

Path-based cache keys break on file moves or renames. Content-hash caching uses SHA-256 file content as the cache key instead of the file path, ensuring cache entries remain valid and survive directory changes automatically.

Content hashing provides automatic cache invalidation because the SHA-256 hash is derived from the file's content. When a file's content changes, its hash changes, bypassing the old cache entry and triggering fresh processing automatically.

The best way to cache PDF parsing and text extraction results is using a service-layer wrapper around your processing function. This keeps processing logic pure while storing cached outputs as {hash}.json for direct O(1) lookups without an index.

Yes, you can use file-based storage for caching image analysis pipelines. This pattern stores cache entries as individual {hash}.json files, enabling direct O(1) lookups without requiring a database or external index.

Avoid content-hash caching when file processing is inexpensive or when files are processed only once. Computing SHA-256 hashes adds overhead, so this pattern is best suited for cost-heavy pipelines like OCR where the same files are processed repeatedly.