xixirangrang

Remove the PASSWORD() function

2

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best practices: multi-column index optimization

9

### First-time contributors' checklist - [ ] I've signed [**Contributor License Agreement**](https://cla-assistant.io/pingcap/docs) that's required for repo owners to accept my contribution. ### What is changed, added or deleted? (Required) ###...

best practices: add index best practices

3

### First-time contributors' checklist - [ ] I've signed [**Contributor License Agreement**](https://cla-assistant.io/pingcap/docs) that's required for repo owners to accept my contribution. ### What is changed, added or deleted? (Required) ###...