…p#17232)

* support batch cop for tiflash

* support batch cop

* support join push down to tiflash

* refine

* change pb

* push join

* fix

* add hint

* refine hint

* add ranges

* fix

* fix

* fix push down

* fix index

* enable distsql for join

* add a session var to disable/enable broadcast join

* fix bug

* fix bug

* tiny fix

* enable cast decimal pushdown to tiflash

* fix

* fix bc join bug

* make broadcast plan stable

* refine code

* fix bug

* basic support for multi table broadcast join

* fix bug

* basic cbo for broadcast join

* improve

* fix bug

* remote useless code

* add tests

* pass unit tests

* refine code

* support execute summary info for broadcast join

* fix bug in explain for broadcast join

* format code

* remove un-needed code

* fix make dev

* address comments

* Hanfei/join merge (#7)

* enable exec details for batch cop

* format code

* fix test

* change tidb_opt_broadcast_join to global vars

* Ban cartesian join to be pushed down to TiFlash (#8)

* merge master (#10)

* merge master

* fix bug

* fix bug

* fix ut

* check session var conflict

* Add perfer local hint for broadcast join (#12)

* update

* remove useless code

* remove useless code

* update parser

* add test for prefer local join

* use bcj_local

* update go.mod

* refine planner

* refine comments

* fix make dev

* fix make dev

* update parser

* address comments

* fix make dev

* disable broadcast join when new collation is enabled

* Update planner/core/exhaust_physical_plans.go

Co-authored-by: Zhuomin(Charming) Liu <lzmhhh123@gmail.com>

* address comments

* fix

* address comments

* fix tests

* address comments

Co-authored-by: xufei <xufeixw@mail.ustc.edu.cn>
Co-authored-by: xufei <xufei@pingcap.com>
Co-authored-by: 虎 <ichneumon.hu@foxmail.com>
Co-authored-by: Zhuomin(Charming) Liu <lzmhhh123@gmail.com>

…-other` (pingcap#24780)