2a1b2394a2
This PR mainly adds a rewrite rule 'ExtractCommonFactorsRule'
used to extract wide common factors in the planning stage for 'Expr'.
The main purpose of this rule is to extract (Range or In) expressions
that can be combined from each or clause.
E.g:
Origin expr: (1<a<3 and b in ('a') ) or (2<a<4 and b in ('b'))
Rewritten expr: (1<a<4 ) and (b in ('a', 'b')) and ((1<a<3 and b in ('a') ) or (2<a<4 and b in ('b')))
Although the range of the wide common factors is larger than the real range,
the wide common factors only involve a single column, so it can be pushed down to the scan node,
thereby reducing the amount of scanned data in advance and improving the query speed.
It should be noted that this optimization strategy is not for all scenarios.
When filter rate of the wide common factor is too low,
the query will consume an extra time to calculate the wide common factors.
So this strategy can be switched by configuring session vairables 'extract_wide_range_expr'.
The default policy is enabled which means this strategy takes effect.
If you encounter unsatisfactory filtering rate, you can set the variable to false.
It will turn off the strategy.
Fixed #6082
# fe-common This module is used to store some common classes of other modules. # spark-dpp This module is Spark DPP program, used for Spark Load function. Depends: fe-common # fe-core This module is the main process module of FE. Depends: fe-common, spark-dpp