Help Center/ Distributed Database Middleware/ User Guide (Kuala Lumpur Region)/ FAQs/ SQL Syntax/ How Do I Optimize SQL Statements?

Updated on 2022-08-17 GMT+08:00

View PDF

How Do I Optimize SQL Statements?

You are advised to use INNER instead of LEFT JOIN or RIGHT JOIN.
When LEFT JOIN or RIGHT JOIN is used, ON is preferentially executed, and WHERE is executed at the end. Therefore, when using LEFT JOIN or RIGHT JOIN, ensure that the conditions are judged in the ON statement to reduce the execution of WHERE.
When possible, use JOIN instead of subqueries to avoid full scanning of large tables.

Parent topic: SQL Syntax

Previous topic: Does DDM Support Distributed JOIN?

Next topic: Does DDM Support Forced Data Type Conversion?

Feedback

Was this page helpful?

Helpful Not helpful

Provide feedback

Thank you very much for your feedback. We will continue working to improve the documentation.See the reply and handling status in My Cloud VOC.

The system is busy. Please try again later.

Which of the following issues have you encountered?

Content is inconsistent with the product UI

Unclear descriptions

Lack of examples or code

Incorrect steps

Can't find what I need

Lack of best practices

Feedback (optional)

0/500

Select at least one type of issue, and enter your comments or suggestions.

Enter a maximum of 500 characters.

Submit Cancel

For any further questions, feel free to contact us through the chatbot.