3768: Fix bugs in graph-based ranking rules + make `words` a graph-based ranking rule r=dureuill a=loiclec
This PR contains three changes:
## 1. Don't call the `words` ranking rule if the term matching strategy is `All`
This is because the purpose of `words` is only to remove nodes from the query graph. It would never do any useful work when the matching strategy was `All`. Remember that the universe was already computed before by computing all the docids corresponding to the "maximally reduced" query graph, which, in the case of `All`, is equal to the original graph.
## 2. The `words` ranking rule is replaced by a graph-based ranking rule.
This is for three reasons:
1. **performance**: graph-based ranking rules benefit from a lot of optimisations by default, which ensures that they are never too slow. The previous implementation of `words` could call `compute_query_graph_docids` many times if some words had to be removed from the query, which would be quite expensive. I was especially worried about its performance in cases where it is placed right after the `sort` ranking rule. Furthermore, `compute_query_graph_docids` would clone a lot of bitmaps many times unnecessarily.
2. **consistency**: every other ranking rule (except `sort`) is graph-based. It makes sense to implement `words` like that as well. It will automatically benefit from all the features, optimisations, and bug fixes that all the other ranking rules get.
3. **surfacing bugs**: as the first ranking rule to be called (most of the time), I'd like `words` to behave the same as the other ranking rules so that we can quickly detect bugs in our graph algorithms. This actually already happened, which is why this PR also contains a bug fix.
## 3. Fix the `update_all_costs_before_nodes` function
It is a bit difficult to explain what was wrong, but I'll try. The bug happened when we had graphs like:
<img width="730" alt="Screenshot 2023-05-16 at 10 58 57" src="https://github.com/meilisearch/meilisearch/assets/6040237/40db1a68-d852-4e89-99d5-0d65757242a7">
and we gave the node `is` as argument.
Then, we'd walk backwards from the node breadth-first. We'd update the costs of:
1. `sun`
2. `thesun`
3. `start`
4. `the`
which is an incorrect order. The correct order is:
1. `sun`
2. `thesun`
3. `the`
4. `start`
That is, we can only update the cost of a node when all of its successors have either already been visited or were not affected by the update to the node passed as argument. To solve this bug, I factored out the graph-traversal logic into a `traverse_breadth_first_backward` function.
Co-authored-by: Loïc Lecrenier <loic.lecrenier@me.com>
Co-authored-by: Louis Dureuil <louis@meilisearch.com>
3757: Adjust the cost of edges in the `position` ranking rule by bucketing positions more aggressively r=loiclec a=loiclec
This PR significantly improves the performance of the `position` ranking rule when:
1. a query contains many words
2. the `position` ranking rule needs to be called many times
3. the score of the documents according to `position` is high
These conditions greatly increase:
1. the number of edge traversals that are needed to find a valid path from the `start` node to the `end` node
2. the number of edges that need to be deleted from the graph, and therefore the number of times that we need to recompute all the possible costs from START to END
As a result, a majority of the search time is spent in `visit_condition`, `visit_node`, and `update_all_costs_before_node`. This is frustrating because it often happens when the "universe" given to the rule consists of only a handful of document ids.
By limiting the number of possible edges between two nodes from `20` to `10`, we:
1. reduce the number of possible costs from START to END
2. reduce the number of edges that will be deleted
3. make it faster to update the costs after deleting an edge
4. reduce the number of buckets that need to be computed
In terms of relevancy, I don't think we lose or gain much. We still prefer terms that are in a lower positions, with decreasing precision as we go further. The previous choice of bucketing wasn't chosen in a principled way, and neither is this one. They both "feel" right to me.
Co-authored-by: Loïc Lecrenier <loic.lecrenier@me.com>
Co-authored-by: meili-bors[bot] <89034592+meili-bors[bot]@users.noreply.github.com>
3755: Re-add final dot r=curquiza a=ManyTheFish
I removed the final dot of the error message in my last PR, this one re-adds it.
related to https://github.com/meilisearch/meilisearch/pull/3749
> Oups 😬
Co-authored-by: ManyTheFish <many@meilisearch.com>
3741: Add ngram support to the highlighter r=ManyTheFish a=loiclec
This PR fixes a bug introduced by the search refactor, where ngrams were not highlighted.
The solution was to add the ngrams to the vector of `LocatedQueryTerm` that is given to the `MatchingWords` structure.
Co-authored-by: Loïc Lecrenier <loic.lecrenier@me.com>
3749: Fix back: sort error message r=ManyTheFish a=ManyTheFish
This PR reintroduces the error message modified in https://github.com/meilisearch/milli/pull/375.
However, this added double-quotes around `sort` in the message. I don't think another message contains double-quotes, so I have added a separate commit replacing the double-quotes with back-ticks, which seems more consistent with the other error messages, this last change can be reverted easily.
## Detailed changes
#### v1.2-rc0
```
The sort ranking rule must be specified in the ranking rules settings to use the sort parameter at search time.
```
#### [Reintroduce fix (previous and expected behavior)](23d1c86825)
```
You must specify where "sort" is listed in the rankingRules setting to use the sort parameter at search time
```
#### [Replace double-quotes with back-ticks (my suggestion)](4d691d071a)
```
You must specify where `sort` is listed in the rankingRules setting to use the sort parameter at search time
```
## Related
Fixes#3722
## Reviewers
- technical review: `@irevoire`
- to validate the replacement: `@macraig`
Co-authored-by: ManyTheFish <many@meilisearch.com>
3726: Fix prefix highlighting r=loiclec a=ManyTheFish
The prefix queries were not properly highlighted, this PR now highlights only the start of a word when it matched with a prefix
Co-authored-by: ManyTheFish <many@meilisearch.com>
Co-authored-by: Loïc Lecrenier <loic.lecrenier@me.com>
3687: Allow to disable specialized tokenizations (again) r=Kerollmops a=jirutka
In PR #2773, I added the `chinese`, `hebrew`, `japanese` and `thai` feature flags to allow melisearch to be built without huge specialed tokenizations that took up 90% of the melisearch binary size. Unfortunately, due to some recent changes, this doesn't work anymore. The problem lies in excessive use of the `default` feature flag, which infects the dependency graph.
Instead of adding `default-features = false` here and there, it's easier and more future-proof to not declare `default` in `milli` and `meilisearch-types`. I've renamed it to `all-tokenizers`, which also makes it a bit clearer what it's about.
Co-authored-by: Jakub Jirutka <jakub@jirutka.cz>
In PR #2773, I added the `chinese`, `hebrew`, `japanese` and `thai`
feature flags to allow melisearch to be built without huge specialed
tokenizations that took up 90% of the melisearch binary size.
Unfortunately, due to some recent changes, this doesn't work anymore.
The problem lies in excessive use of the `default` feature flag, which
infects the dependency graph.
Instead of adding `default-features = false` here and there, it's easier
and more future-proof to not declare `default` in `milli` and
`meilisearch-types`. I've renamed it to `all-tokenizers`, which also
makes it a bit clearer what it's about.
