planner: FTS query enhancements
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report/customer
sig/planner
type/enhancement
- Dominant language
- Go
- Stars
- 40.6k
- Forks
- 6.2k
- PR merge metrics
- PR metrics pending
Description
Enhancement
We identified several potential enhancements for FTS queries on the optimizer:
- The LIKE fallback can't support quoted words, for example,
match(col) against('"word"')is not support, but actually it has the same semantic withmatch(col) against('word'), we should support it. - The default estimation of
match againstismin(rows/10, 1000), which is not good for large tables with low NDV; A better formula could berows/NDV. - Sometimes the optimizer could return this error
No access path for table 't' is found with 'tidb_isolation_read_engines' = 'tikv,tiflash,tidb', valid values can be 'tici'. Please check tiflash replica., we should fix it.
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
The issue names no files or tests. Start by locating the optimizer's FTS query handling and reproduce the quoted-word LIKE fallback, match-against estimation, and tidb_isolation_read_engines error. Done should cover the three proposed behaviors with regression tests.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- go, sql
- Domain
- databases
- Issue type
- Feature
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Quiet
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100