MeiliSearch/milli
bors[bot] ea4bb9402f
Merge #483
483: Enhance matching words r=Kerollmops a=ManyTheFish

# Summary

Enhance milli word-matcher making it handle match computing and cropping.

# Implementation

## Computing best matches for cropping

Before we were considering that the first match of the attribute was the best one, this was accurate when only one word was searched but was missing the target when more than one word was searched.

Now we are searching for the best matches interval to crop around, the chosen interval is the one:
1) that have the highest count of unique matches
> for example, if we have a query `split the world`, then the interval `the split the split the` has 5 matches but only 2 unique matches (1 for `split` and 1 for `the`) where the interval `split of the world` has 3 matches and 3 unique matches. So the interval `split of the world` is considered better.
2) that have the minimum distance between matches
> for example, if we have a query `split the world`, then the interval `split of the world` has a distance of 3 (2 between `split` and `the`, and 1 between `the` and `world`) where the interval `split the world` has a distance of 2. So the interval `split the world` is considered better.
3) that have the highest count of ordered matches
> for example, if we have a query `split the world`, then the interval `the world split` has 2 ordered words where the interval `split the world` has 3. So the interval `split the world` is considered better.

## Cropping around the best matches interval

Before we were cropping around the interval without checking the context.

Now we are cropping around words in the same context as matching words.
This means that we will keep words that are farther from the matching words but are in the same phrase, than words that are nearer but separated by a dot.

> For instance, for the matching word `Split` the text:
`Natalie risk her future. Split The World is a book written by Emily Henry. I never read it.`
will be cropped like:
`…. Split The World is a book written by Emily Henry. …`
and  not like:
`Natalie risk her future. Split The World is a book …`


Co-authored-by: ManyTheFish <many@meilisearch.com>
2022-04-19 11:42:32 +00:00
..
fuzz Update heed link in cargo toml 2022-03-01 19:45:29 +01:00
src Merge #483 2022-04-19 11:42:32 +00:00
tests add test for disctinct nb hits 2022-04-13 12:10:35 +02:00
Cargo.toml Update version for the next release (v0.26.1) 2022-04-14 11:44:06 +02:00
README.md update the readme + dependencies 2022-01-12 18:30:11 +01:00

Milli

Fuzzing milli

Currently you can only fuzz the indexation. To execute the fuzzer run:

cargo +nightly fuzz run indexing

To execute the fuzzer on multiple thread you can also run:

cargo +nightly fuzz run -j4 indexing

Since the fuzzer is going to create a lot of temporary file to let milli index its documents I would also recommand to execute it on a ramdisk. Here is how to setup a ramdisk on linux:

sudo mount -t tmpfs none path/to/your/ramdisk

And then set the TMPDIR environment variable to make the fuzzer create its file in it:

export TMPDIR=path/to/your/ramdisk