mysql query performance tuning

This article mainly introduces the distinct statement in MySQL to query duplicate records and related performance discussions. the point in this article is to avoid using distinct in top-level queries under certain circumstances, for more information, see MySQL Query. duplic

the various types of fields are stored, more importantly, how the database data storage, how to partition, how to manage, such as Oracle's data files, table space, segments, and so on. Understanding this mechanism can alleviate a lot of I/O load. For example: Using show engines under MySQL, you can see the support of various storage engines. Different storage engines have different priorities, and for different business or database designs you will h

very good for caching, for complex SELECT statements can use the query cache, but it should be noted that the table on the update, DELETE, insert operation compared to select is very few.3, query Cache hit ratio: qcache_hits/(qcahce_hits+com_select), query cache hit rate is a good hit rate, needs specific analysis. As long as the

Tags: large number of advance group Check life cycle entry Expression src No This article is "high-performance MySQL" Reading notes Slow Query Basics: Optimizing data accessThe most basic reason for poor query performance is that there is too much data to acces

Database Tuning tutorial (4) Explain performance analysis command, tuning explain In the previous chapter, we learned how to find slow queries and record statements into logs. How can we know where statement problems occur after slow queries are found. This chapter describes how to use the database performance analysis

High-Performance MySql evolution (10): Limitations of the query optimizer bitsCN.com The article "common methods of the query optimizer" lists some common optimization methods of the optimizer. The query optimizer also has some limitations while providing these features. the

Statistics update inserted values Determining the order in which values are taken Write a lazy Union Other uses of user-defined variables Query run-time calculation totals and averages function first () and last () in the simulation group statement Do some data calculations on a large amount of data Calculates the MD5 hash value of a large table Write a sample processing function to ch

MySQL queries random data in four ways and performance comparison below from the following four solutions to analyze their respective advantages and disadvantages. Solution 1:SELECT * FROM 'table' order by rand () LIMIT 0, 1; This method is very slow. The reason is that MySQL creates a zero-time table to store all result sets, then creates a random index for eac

I will share 11 practical tips on Java performance tuning and java Tuning Most developers think that performance optimization is a complicated problem and requires a lot of experience and knowledge. Yes, it is not wrong. It is not easy to optimize the application to achieve the best

Label:Objective About SQL Server Tuning series is a huge content system, not a word two words can be analyzed clearly, this article first in the SQL tuning in the most commonly used query plan to parse, to do a good job of the basic grasp, tamping basic skills! Then we talk about the overall statement tuning. Learn how

| +---------------------+-------+ The configuration of the record slow query, the execution time of more than 2 seconds is slow query, the system shows that there are 4,148 slow query, you can analyze the slow query log, find the problem of SQL statements, slow query time

wait for the lock ). For example: thread 1 does 1000 insertsthread 2, 3, and 4 does 1 insertthread 5 does 1000 inserts If you do not use the lock, 2, 3, and 4 will be completed before 1 and 5. If you use locking, 2, 3, and 4 may not be completed before 1 or 5, but the overall time should be about 40% faster. Because INSERT, UPDATE, and DELETE operations are fast in MySQL, you will get better overall performance