baishen

**Summary** Refactor aggregating index using materialized view based on the paper [Optimizing queries using materialized views: A practical, scalable solution.](https://sigmodrecord.org/publications/sigmodRecord/0106/pdfs/Optimizing%20Queries%20Using%20Materialized%20Views_%20A%20practical,%20scalable%20solution.pdf)

Databend uses tantivy to implement inverted index, and tantivy `Searcher` needs to read all the index file data when starting up, which is very large, resulting in poor query performance....

Feature: Support map lambda functions

1

**Summary** - `map_filter(map, lambda_expr)` - `map_transform_keys(map, lambda_expr)` - `map_transform_values(map, lambda_expr)` for example: ```sql SELECT map_filter({1:0,2:2,3:-1}, (k, v) -> k > v); SELECT map_transform_keys({1:1,2:2,3:3}, (k, v) -> k + 1); SELECT...

**Summary** We have implemented the basic function of dictionary using `Redis` and `MySQL` as data source #15901 , need to continue test and optimize performance, also improve stability to meet...