planner: allow the optimizer to cache query plans accessing generated columns

[qw4990]

Enhancement

Work Item Tracking

• A fix-control switch (False by default) to control whether to allow the optimizer to cache plans using generated columns and MVIndexes planner: introduce a new fix-control flag to control whether to cache plans that access generated columns #48011
• Extend existing random UTs about MVIndexes to test Plan Cache + generated columns + MVIndex planner: add more test cases for plan cache with generated columns #51314
• Collect all users' existing queries and add them as UTs planner: add more test cases for plan cache with generated columns #51323
• Collect related cases from index.test to test Plan Cache + MVIndex planner: add more test cases for plan cache with generated columns #51483
• Collect related cases from multi_valued_index.test, multi_valued_index.test to test Plan Cache + MVIndex planner: add more test cases for plan cache with generated columns #51510
• When encountering cases that json_contains/overlaps lead to uncacheable plans, choose to generate optimal plans without caching rather than caching sub-optimal plans planner: choose to generate optimal plans without plan cache rather than generating suboptimal plans and caching it when generating MVIndex plans #51546
• Enable the fix-control switch by default after finishing all the above tasks planner: allow the optimizer to cache query plans accessing generated columns by default #51654

Description

Currently, queries below are not allowed to be cached since these queries are accessing generated columns:

create table t1 (
    a int,
    info json,
    city varchar(64) as (JSON_UNQUOTE(JSON_EXTRACT(info, '$.city')))
);
prepare s1 from 'select * from t1 where a=?';
show warnings;

create table t2 (
    a int,
    info json,
    city varchar(64) as (JSON_UNQUOTE(JSON_EXTRACT(info, '$.city'))) virtual
);
prepare s2 from 'select * from t2 where a=?';
show warnings;

create table t3 (
    a int,
    info json,
    city varchar(64) as (JSON_UNQUOTE(JSON_EXTRACT(info, '$.city'))) stored
);
prepare s3 from 'select * from t3 where a=?';
show warnings;

create table t4 (
    a int,
    info json,
    index zips( (CAST(info->'$.zipcode' AS UNSIGNED ARRAY)))
);
prepare s4 from 'select * from t4 where a=?';
show warnings;

mysql> show warnings;
+---------+------+----------------------------------------------------------------------------+
| Level   | Code | Message                                                                    |
+---------+------+----------------------------------------------------------------------------+
| Warning | 1105 | skip prepared plan-cache: query accesses generated columns is un-cacheable |
+---------+------+----------------------------------------------------------------------------+
1 row in set (0.00 sec)