Initialize metadata and tag indexing encoding for RediSearch

[PragmaTwice]

It close #2065.

The current encoding design:

search data type metadata:

key (index name) -> flag | expire | version | size | on_data_type (HASH or JSON)

prefixes encoding:

key (index name) | PREFIXES -> prefix1 prefix2 ...

tag field metadata encoding:

key (index name) | TAG_FIELD_META | field name -> separator | case sensitive

tag field index encoding:

key (index name) | TAG_FIELD | field name | tag | key -> (nil)

Refs:
https://redis.io/docs/interact/search-and-query/
https://redis.io/docs/interact/search-and-query/advanced-concepts/tags/

[mapleFU]

How can we list all indexes efficiently? 🤔
RediSearch seems would tracking the records for insert and maintaining index on that, should we support some global tracking structure?

[PragmaTwice]

How can we list all indexes efficiently? 🤔 RediSearch seems would tracking the records for insert and maintaining index on that, should we support some global tracking structure?

Like RediSearch, we will track all HASH and JSON commands and adjust our indexes accordingly.

[mapleFU]

Like RediSearch, we will track all HASH and JSON commands and adjust our indexes accordingly.

I mean, when start the process, we should "LIST" all indexes

[PragmaTwice]

Like RediSearch, we will track all HASH and JSON commands and adjust our indexes accordingly.

I mean, when start the process, we should "LIST" all indexes

Ahh I got your point.

I think we can add a common prefix for all index key, or put them to a new CF. Currently I prefer the latter.

[git-hulk]

Like RediSearch, we will track all HASH and JSON commands and adjust our indexes accordingly.

I mean, when start the process, we should "LIST" all indexes

Ahh I got your point.

I think we can add a common prefix for all index key, or put them to a new CF. Currently I prefer the latter.

This skeleton code looks good to me. I also prefer the latter one if we want to keep the common prefix since the current column families are not for this purpose. But we need to do a little backward compatibility work while adding a new column family.

[sonarcloud]

Quality Gate passed

The SonarCloud Quality Gate passed, but some issues were introduced.

3 New issues
0 Security Hotspots
60.5% Coverage on New Code
1.0% Duplication on New Code

See analysis details on SonarCloud

[mapleFU]

So only "tag" is support currently?

[PragmaTwice]

So only "tag" is support currently?

Yeah, I also plan to add the support of numeric indexes.

But for text and vector fields, it is currently not in the plan.