Followup to #20915. If we're grouping search results that don't rely on core's search, we won't have access to pg headlines. This is now configurable via the constructor, defaulting to `SiteSetting.use_pg_headlines_for_excerpt`
- Reduce duplication of terms in post index from unlimited to 6. This will
result in reduced index size and reduced weighting for posts containing
a huge amount of duplicate terms. (Eg: a post containing "sam sam sam sam
sam sam sam sam", will index as "sam sam sam sam sam sam", only including
the word up to 6 times.) This corrects a flaw where title weighting could
be ignored.
- Prioritize exact matches of words in titles. Our search always performs
a prefix match. However we want to give special weight to exact title matches
meaning that a search for "sum" will find topics such as "the sum of us" vs
"summer in spring".
- Pick up fixes to our search algorithm which are missing from old indexes.
Specifically pick up the fix that indexes URLs properly. (`https://happy.com`
was stemmed to `happi` in keywords and then was not searchable)
see also:
https://meta.discourse.org/t/refinements-to-search-being-tested-on-meta/254158
Indexing will take a while and work in batches, in the background.
When searching for PMs or PMs in a group inbox, results in the header search were not being limited to 5 with a "More" link to the full page search. This PR fixes that.
It also simplifies the logic and updates the search API docs to include recently added `in:messages` and `group_messages:groupname` options.
The search_ignore_accents site setting can be used to make the search
indexer remove the accents before indexing the content. The unaccent
function from PostgreSQL is better than Ruby's unicode_normalize(:nfkd).
* Chinese segmenetation will continue to rely on cppjieba
* Japanese segmentation will use our port of TinySegmenter
* Korean currently does not rely on segmentation which was dropped in c677877e4fe5381f613279901f36ae255c909573
* SiteSetting.search_tokenize_chinese_japanese_korean has been split
into SiteSetting.search_tokenize_chinese and
SiteSetting.search_tokenize_japanese respectively
Previously we used the raw data indexed to generate blurbs even for cases
when Chinese/Korean/Japanese text was used.
This caused superfluous spaces to show up in excerpts.
In the near future, we will be swtiching to PG headlines to generate the
search blurb. As such, we need to replace audio and video links in the
raw data used for headline generation. This also means that we avoid
replacing links each time we need to generate the blurb.
The global setting disable_search_queue_threshold
(DISCOURSE_DISABLE_SEARCH_QUEUE_THRESHOLD) which default to 1 second was
added.
This protection ensures that when the application is unable to keep up with
requests it will simply turn off search till it is not backed up.
To disable this protection set this to 0.
This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
