MySQL de-duplication query efficiency optimization skills The actual combat strategy of tens of millions of data tables

When dealing with database applications with high concurrency and massive data, the efficiency of MySQL deduplication query often becomes a performance bottleneck.

This article will share some practical skills and strategies to help you achieve efficient deduplication operations in million-level data tables, thereby improving overall database performance.

I. Understand the basic principle of MySQL deduplication algorithm.

First, we need to understand the basic principle of MySQL deduplication algorithm.

De-duplication algorithms usually include de-duplication based on hash value and de-duplication based on string comparison.

For tens of millions of data tables, we should prioritize the use of more efficient hash deduplication methods.

2. Reasonable indexing strategy.

To speed up the query, we can create a composite index for deduplicated fields.

For example, if you have a table containing user information and you want to deduplicate based on the user's email address, you can create a composite index:

CREATE INDEX idx_email ON users (email);

This index can significantly improve query efficiency because it allows the database to quickly locate records with the same email address.

3. Utilize window functions and aggregate functions.

The window functions and aggregation functions provided by MySQL can handle large-scale data more flexibly.

For example, using ROW_NUMBER()The window function sorts the deduplicated data, and then combines GROUP BYSumHAVINGClause filters out non-repeating records, which avoids unnecessary full table scans.

The following is an example SQL statement to get a unique record of each mailbox address from the user information table:

SELECT * FROM (
    SELECT *, ROW_NUMBER() OVER (PARTITION BY email ORDER BY id) as row_num
    FROM users
) AS subquery
WHERE row_num = 1;

In this query, ROW_NUMBER()The function generates a unique line number for each email address, and then filters the record with the line number 1 through an external query, that is, the unique record of each email address.

Fourth, reasonably configure the configuration parameters of MySQL.

Reasonable configuration of MySQL configuration parameters also helps to improve database performance.

Especially for tens of millions of data tables, increasing the buffer pool size can reduce memory pressure and reduce lock waiting time.

Here are some key configuration parameters: \n-innodb_buffer_pool_size: This parameter determines the size of the buffer pool that the InnoDB storage engine can use.

Increasing this value can increase the cache hit rate, thereby improving query performance.

\n-innodb_flush_log_at_trx_commit: This parameter controls the frequency of transaction log refreshes.

Setting it to 2 reduces disk I/O operations, but may increase the risk of data loss.

You can configure the file in MySQL (usually my.cnfOrmy.ini) to set these parameters:

[mysqld]
innodb_buffer_pool_size = 4G
innodb_flush_log_at_trx_commit = 2

V. Regularly maintain and analyze database performance logs.

Regularly maintaining and analyzing database performance logs can help us identify and address potential performance issues.

By observing the slow query log, we can locate the SQL statements that lead to performance degradation, and then perform targeted optimization.

The method to enable slow query log is as follows:

SET GLOBAL slow_query_log = 'ON';
SET GLOBAL long_query_time = 1; -- 设置慢查询阈值为1秒

Then, you can view the slow query log file and find the SQL statement that needs to be optimized.

VI. Summary.

Improving the efficiency of MySQL deduplication query of tens of millions of data tables requires comprehensive consideration of algorithm selection, index optimization, configuration tuning, and performance monitoring.

By practicing these strategies, you can effectively improve database performance and meet the needs of high concurrency and massive data scenarios.

I hope this article can help you achieve good results in practice.