BFF

The big friendly filter 😁 (originally written by Dirk @ AI2, updated by me)

Getting started

1. Install Rust on your machine.
   1. curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
   2. Add ~/.cargo/bin to your PATH environment variable.
2. Run cargo build --release. It places the binary at target/release/bff.
3. Run ./target/release/bff --help to see the available options.

Examples

There are three modes bff (local input -> local output), bff-remote (S3 input -> S3 output), and sysreq (for assessing system requirements). We always need an input, output, false positive rate, and expected number of ngrams. But then there's some optional hyperparameters:

• --min-ngram-size: In pargraph/both mode, we ignore any paragraphs shorter than this. Defaults to 5.
• --max-ngram-size: The "working width" of shinglings of ngrams: e.g., for long paragraphs/documents, we check membership over ngrams of this size. Defaults to 13.
• --filtering-threshold: If at least this fraction of ngrams is present, we remove the entire paragraph/document. Defaults to 0.8

And some REMOTE ONLY arguments:

• --shard-num: For large nummbers of files, sharding is helpful. This selects some subset of the files. Defaults to 0
• --num-shards: Dictates how many shards we have. Defaults to 1.

Deduplicating local files:

For files that exist locally, say a directory to_be_deduped/, we can output deduplicated versions of these files in has_been_deduped/ like:

   --inputs to_be_deduped \
   --output-directory has_been_deduped \
   --expected-ngram-count 12345678 \
   --fp-rate 0.01

Deduplicating remote files

For files that exist on S3, say with the prefix s3://my-bucket/to_be_deduped/, we can output deduplicated versions of these files in s3://my-bucket/has_been_deduped like:

--bucket my-bucket \
--input-dir to_be_deduped \
--output_dir has_been_deduped \
--expected-ngram-count 12345678 \\
--fp-rate 0.01

There's also some options to preload or save the bloom filter itself, but you can check the code for those.