feat: distinguish between different read paths

[v0y4g3r]

I hereby agree to the terms of the GreptimeDB CLA

What's changed and what's your intention?

This PR handles different read/freeze paths of DataBuffer in different components 😵‍💫

• For DataBuffer::read inside ShardBuilder

  • pk_weights must be present, yielded rows are sorted according to weights
  • replace_pk_index set to false as pk dict are not frozen yet
  • keep_data set to true

• For DataBuffer::freeze inside ShardBuilder

  • pk_weights must be present, yielded rows are sorted according to weights
  • replace_pk_index set to true so that yielded DataPart contains only weights
  • keep_data set to false as we need to take the values

• For DataBuffer::read inside Shard

  • pk_weights set to None as DataBuffer in Shard has already replaced pk_index with weights, rows are sorted by "pk_index" directly
  • replace_pk_index set to false for the same reason
  • keep_data set to true

• For DataBuffer::freeze inside Shard

  • pk_weights set to None as DataBuffer in Shard has already replaced pk_index with weights, rows are sorted by "pk_index" directly
  • replace_pk_index set to false for the same reason
  • keep_data set to false as we need to take the values

Checklist

• I have written the necessary rustdoc comments.
• I have added the necessary unit tests and integration tests.
• This PR does not require documentation updates.

Refer to a related PR or issue link (optional)

[codecov]

Codecov Report

Attention: Patch coverage is 96.08939% with 7 lines in your changes are missing coverage. Please review.

Project coverage is 85.16%. Comparing base (b144836) to head (d43ddaf).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3369      +/-   ##
==========================================
- Coverage   85.56%   85.16%   -0.40%     
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  Files         892      892              
  Lines      146412   146543     +131     
==========================================
- Hits       125282   124810     -472     
- Misses      21130    21733     +603     

[evenyag]

LGTM

[waynexia]

Believe it's good