pingcap / pingcap/tiflash

Use Ryū or DragonBox algorithm library to speed up float-to-string conversion

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type/enhancement
Dominant language
C++
Stars
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Forks
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Avg merge
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Merged PRs (30d)
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Description

Enhancement

Ryū paper: https://dl.acm.org/doi/pdf/10.1145/3296979.3192369
Ryū C++ implementation by author: https://github.com/ulfjack/ryu

BTW, the strconv in Go's standard library has already used Ryū algorithm. (See https://github.com/golang/go/issues/15672).

DragonBox: https://github.com/jk-jeon/dragonbox

TiFlash uses https://github.com/google/double-conversion to convert float to string.
Clickhouse changed double-conversion to Ryu in this PR https://github.com/ClickHouse/ClickHouse/pull/8542.
Then it changed to DragonBox in this PR https://github.com/ClickHouse/ClickHouse/pull/17831.

We need to investigate it further to choose which one will be used.

Contributor guide

No contributing guide indexed for this repository

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 comparing the Ryū, DragonBox, and double-conversion references linked in the issue, including the cited ClickHouse changes and Go's strconv implementation. Investigate which library TiFlash should use; done means documenting a selected algorithm and the basis for that choice.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
databases, performance
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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