pingcap / pingcap/tiflash

The block returned by `InputStream` should obey the `max_block_size` constraint

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component/compute severity/moderate type/enhancement
Dominant language
C++
Stars
1k
Forks
423
Avg merge
1d 15h
Merged PRs (30d)
24

Description

In TiFlash there is a setting named max_block_size, which means the max number of rows for each block, so the block returned by InputStream should obey this constraint.
Currently, most of the InputStream obeys this constraint except for aggregation and join, the size of block returned by aggregation and join is un-limited, should find a way to fix this.

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by tracing the aggregation and join implementations of InputStream and how they handle the max_block_size setting. Compare them with the other InputStream implementations that already obey the constraint; done means blocks returned by aggregation and join do not exceed the configured row limit.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
databases
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
35/100

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