Bloom is a simple tool that provides a very efficient implementation of Bloom filters for the go language. It provides a command line tool that can be used to easily create Bloom filters with desired capacity and false positive probability. Values can be added to filters through standard input, which makes it easy to use the tool in a pipeline workflow.

To create a new bloom filter with a desired capacity and false positive probability, you can use the create command:

#will create a gzipped Bloom filter with 100.000 capacity and a 0.1 % false positive probability
bloom --gzip create -p 0.001 -n 100000 test.bloom.gz

To insert values, you can use the insert command and pipe some input to it (each line will be treated as one value):

cat values | bloom --gzip insert test.bloom.gz

You can also interactively add values to the filter by specifying the --interactive command line option:

bloom --gzip --interactive insert test.bloom.gz

To check if a given value or a list of values is in the filter, you can use the check command:

cat values | bloom --gzip check test.bloom.gz

This will return a list of all values in the filter.

Sometimes it is useful to attach additional information to a string that we want to check against the Bloom filter, such as a timestamp or the original line content. To make passing along this additional information easier within a shell context, the Bloom tool provides an option for splitting the input string by a given delimiter and checking the filter against the resulting field values. Example:

# will check the Bloom filter for the values foo, bar and baz
cat "foo,bar,baz" | bloom -s filter.bloom

# uses a different delimiter (--magic-delimiter--)
cat "foo--ac5ba--bar--ac5ba--baz" | bloom  -d "--ac5ba--" -s filter.bloom

# will check the Bloom filter against the second field value only
cat "foo,bar,baz" | bloom -f 1 -s filter.bloom

# will check the Bloom filter against the second and third field values only
cat "foo,bar,baz" | bloom -f 1,2 -s filter.bloom

# will print one line for each field value that matched against the filter
cat "foo,bar,baz" | bloom -e -s filter.bloom

# will print the last field value for each line whose fields matched against the filter
cat "foo,bar,baz" | bloom -e -s --pf -1 filter.bloom

This functionality is especially handy when using CSV data, as it allows you to filter CSV rows by checking individual columns against the filter without having to use external tools to split and reassemble the lines.

To install the command line tool:

make install

To run the tests:

make test

To run the benchmarks:

make bench