cherry-pick #2125 to release-4.0
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/2127

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

git push git@github.com:ti-srebot/tics.git pr/2127:release-4.0-46b829485358

What problem does this PR solve?

Issue Number: close #2118

Problem Summary:

DeltaTree add a "_tidb_rowid" column to the table even if "pk is handle" is true. We use the FunctionToInt64 to copy data from the primary key column to the handle column under this situation.

https://github.com/pingcap/tics/blob/1078d0b8199a1cfe54d73623ea8da636505f419b/dbms/src/Storages/DeltaMerge/DeltaMergeStore.cpp#L403-L410

However, if the types are identical, FunctionToInt64 only does a shallow copy and makes the primary key column and _tidb_rowid share the same column ptr when "pk is handle".

https://github.com/pingcap/tics/blob/1078d0b8199a1cfe54d73623ea8da636505f419b/dbms/src/Functions/FunctionsConversion.h#L832-L841

After that, we need to reorganize the boundary of blocks, this makes us append some rows into the pk column and handle column. Unfortunately, they share the same column pointer, which makes the columns inside one block don't align and make trouble for later processing.
https://github.com/pingcap/tics/blob/1078d0b8199a1cfe54d73623ea8da636505f419b/dbms/src/Storages/DeltaMerge/PKSquashingBlockInputStream.h#L75-L99

What is changed and how it works?

Use deep copy instead of shallow copy when the types are identical in DeltaMergeStore::addExtraColumnIfNeed.

Related changes

• PR to update pingcap/docs/pingcap/docs-cn:
• Need to cherry-pick to the release branch:

Check List

Tests

• Unit test

Side effects

Release note

• No release note