pingcap / pingcap/tiflash

Improve the memory usage in `SingleValueDataString`

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

Description

Enhancement

SingleValueDataString will allocate memory from arena when there is large string to be processed. In extreme case, if the length of processed string increases one by one, arena will continuous allocate new memory and the memory that allocated before will be wasted.

Contributor guide

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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 locating SingleValueDataString and tracing how it allocates memory from the arena while processing large strings. Reproduce the case where string length increases one by one, then verify that previously allocated memory is not continuously wasted.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
databases, performance
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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