cherry-pick #1961 to release-5.0
You can switch your code base to this Pull Request by using git-extras:

# In tics repo:
git pr https://github.com/pingcap/tics/pull/2063

After apply modifications, you can push your change to this PR via:

git push git@github.com:ti-srebot/tics.git pr/2063:release-5.0-30db147cf19f

Signed-off-by: JaySon-Huang jayson.hjs@gmail.com

What problem does this PR solve?

Issue Number: #1942

We need to support pushing down the str_to_date function to TiFlash

What is changed and how it works?

• Pick str_to_date function push down (for poc) #1960 and Fix bug for str_to_date nullable input column #1984 to master
• Fix bug for parsing two-digits year number like parsing "03" with format "%Y"
• Support calling str_to_date on two string column

Known issue

pingcap/tidb#24928

• "%D","%j","%U","%u","%V","%v","%W","%w","%X","%x","%%" are neither supported by TiFlash nor TiDB
  https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_date-format

2. TiDB has some incompatible parsing results compare with MySQL, the compatible issues are fixed in this PR, but not fixed by TiDB yet (maybe we should also fix them on the TiDB side to make TiDB and TiFlash be consistent)
   • '%b'/'%M' should be case insensitive
   • Parsing an empty string
   • Parsing the day that does not exist in the real world
   • Parsing the "Feb 29th" for leap year and non-leap year
   • Parsing some input for "%r" and "%T"

Related changes

• Need to cherry-pick to the release branch: 5.0

Check List

Tests

• Unit test

Side effects

Release note

• Support pushing down the str_to_date function to TiFlash