Does manticore sql_range_step support negative values, and does manticore change negative sql return values to positive values like sphinx?

We currently use Sphinx 2.2 and have recently found out about Manticore.
We currently index data from the oldest to newest(id is increased) in Sphinx.
We use ngram_len =1 for CJK indexing but have poor performance for common letters(indexing about 45GB of sphinx CJK data).

On out tests using cutoff and putting the data in newest to oldest in Sphinx, we would be able to solve the very slow queries by having Sphinx not search the whole index.
However, Sphinx does not support negative values in sql_range_step so we could not index backwards from newest to oldest so that we could use cutoff.

Also we have already have negative index values for the id as negative(id) in MySQL. This allows us to use asc indexes in mysql which are faster than desc. However, when we tried this method since negative sql_range_step are not supported in Sphinx, we noticed that Sphinx converts all the negative values to positive values for $start and $end.

Therefore we have four questions regarding Manticore search.
1
Does Manticore sql_range_step support negative values

2
Does Manticore change negative sql return values to positive values like Sphinx?

3
Would Manticore have superior performance regarding ngram_len = 1 compared to Sphinx?

4
Does stopwords = ko for Manticorehave an effect on ngram_len = 1?

5
Are there any way to use an Analyzer for Korean language in Manticore?

Thank you.

could you use icu morphology to instead of ngram ?

I noticed a Manticore tutorial and blog post regarding icu for chinese, does it support Korean too?
I didn’t think it did.
Even if it did, I would guess tests would needed, but often unless well made often ngram will show better results for uesrs.

negative ranges should be also tested as we did not touch that part but add features to RT indexes

Just a note, after additional testing on Sphinx 2.2 we realized:
sql_range_step negative values are meaningless as the order that sphinx searches in actually the id value regardless of the order you index

So that is a feature that is unnecessary considering the current way sphinx searches work

We just needed to optimize the select sql statements more.

We plan to test and migrate to Manticore and also see results to see if any difference for ngram performance(although we expect similar overall performance).

Thanks for replies.

I noticed a Manticore tutorial and blog post regarding icu for chinese, does it support Korean too?

Not yet.

We plan to test and migrate to Manticore and also see results to see if any difference for ngram performance(although we expect similar overall performance).

I don’t think there will be a significant difference as we didn’t optimize it.

Just a note, I tested on identical hardware with same cpu, ram, and nvme drives.
CentOS 8
sphinx-2.2.11-15.el8.x86_64 versus manticore-3.5.0_200722.1d34c491-1.el8.x86_64
Test index size 18GB of Korean language.

Actually I noticed for a example slow Korean query I had, manticore is about 2.6 times slower.
To remove other effects I ran several queries using mysql client 20 times in a row with little variation after multiple runs of the same query.

Other Korean test queries showed varying amounts of slowness to some showing similar performance, with no test queries showing faster results in Manticore search.

On the other hand I tested less English queries they are so fast in both and the real world speed difference is not that important, but for English queries Manticore seems superior in performance and faster results.

I think CJK queries actually got significantly slower in Manticore somehow and hope in future maybe that can be improved, while Manticore seems to have improved English search enough that simple tests show that it is faster.

it could be better to create ticket at Github there to put index config, index statistics ( documents count, fields count ) and queries along with times for them for Manticore and Sphinx to be able to reproduce the issue and check perf

Additional note:
I just tested Sphinx 3.3.1
I noticed cjk settings and related error messages in Manticore are more similar to Sphinx 3.3.1 than Sphinx 2.2.11

I tested on Sphinx 3.3.1 and found the performance slower than Sphinx 2.2.11 for CJK.
I think Manticore maybe using more modern Sphinx code for CJK which is actually slower than 2.2.11 code for CJK.