MYSQL BACKEND: Tối ưu hoá phân trang từ 7s còn 1s với Table có 10.000.000 dữ liệu, SẾP tăng lương...

Summary

In this video, the presenter discusses optimizing database performance, specifically focusing on pagination techniques and indexing strategies. Through practical examples, they demonstrate how to improve query speeds, highlighting the importance of using appropriate indexes and structuring queries effectively. The presenter explains the pitfalls of certain pagination methods and shares insights on using LIMIT and OFFSET efficiently. By comparing execution times before and after optimization, they show a significant reduction from 6 seconds to just 1 second for complex queries. This session aims to equip viewers with valuable tools for enhancing database operations.

Takeaways

• 😀 Optimizing database performance can significantly reduce query execution time, demonstrated by a reduction from 6 seconds to 1 second.
• 😀 Understanding the importance of indexing is crucial; proper indexing can enhance query efficiency and speed.
• 😀 Pagination strategies vary, with traditional methods like LIMIT and OFFSET being less efficient for large datasets.
• 😀 Google’s pagination approach allows for better tracking of records across pages, avoiding the pitfalls of infinite scrolling.
• 😀 The cardinality of indexed columns influences performance; low cardinality can lead to inefficient queries.
• 😀 Using EXPLAIN commands helps analyze query performance and identify whether indexes are being utilized.
• 😀 Avoiding SELECT * and retrieving only necessary fields can drastically improve performance.
• 😀 Implementing temporary tables for complex queries can optimize performance by reducing data load.
• 😀 Properly ordering query results and using multiple criteria can prevent performance degradation due to duplicate values.
• 😀 Continuous assessment and refinement of indexing strategies are essential for maintaining database performance as data grows.

Q & A

What was the initial performance time before optimization?

The initial performance time was 6 seconds before optimization.

What is the significance of pagination in database optimization?

Pagination is crucial for managing large datasets efficiently, allowing for quicker retrieval and better user experience.

What are some common pagination methods discussed in the video?

The video discusses several methods including limit-offset and cursor-based pagination, each with its own advantages and disadvantages.

Why is indexing important in SQL queries?

Indexing is important because it improves the speed of data retrieval operations, making queries faster and more efficient.

What happens to query performance as the dataset size increases?

As the dataset size increases, query performance typically degrades, leading to longer execution times.

What is the 'explain' command used for in SQL?

'Explain' is used to analyze how a SQL query will be executed, showing whether indexes are being used and how the database plans to access data.

How did the speaker demonstrate the effect of indexing on query performance?

The speaker demonstrated that after adding an index, query execution time improved significantly, dropping from 6 seconds to 1 second.

What is the suggested approach to avoid using SELECT * in queries?

It is recommended to avoid using SELECT * and instead specify only the columns needed to reduce data load and improve performance.

What technique was proposed to further optimize query performance?

The speaker suggested using temporary tables to hold intermediate results, which can streamline data retrieval and improve speed.

What overall improvement in performance was achieved after optimization?

After optimization, the performance improved from 6 seconds to 1 second for the same query.