


How to record the use of mysql performance query process_PHP tutorial
It all started from an experiment, please see the example below:
Table:
CREATE TABLE IF NOT EXISTS `foo` (
` a` int(10) unsigned NOT NULL AUTO_INCREMENT,
`b` int(10) unsigned NOT NULL,
`c` varchar(100) NOT NULL,
PRIMARY KEY (`a`),
KEY `bar` (`b`,`a`)
) ENGINE=InnoDB;
CREATE TABLE IF NOT EXISTS `foo2` (
`a` int(10) unsigned NOT NULL AUTO_INCREMENT,
`b` int(10) unsigned NOT NULL,
`c` varchar(100) NOT NULL,
PRIMARY KEY (`a`),
KEY `bar` (` b`,`a`)
) ENGINE=MyISAM;
I inserted 300,000 data into two tables (the performance difference during insertion is that InnoDB is slower than MyISAM)
$host = '192.168.100.166';
$dbName = 'test';
$user = 'root ';
$password = '';
$db = mysql_connect($host, $user, $password) or die('DB connect failed');
mysql_select_db($dbName, $db);
echo '===================InnoDB============= ==========' . "rn";
$start = microtime(true);
mysql_query("SELECT SQL_NO_CACHE SQL_CALC_FOUND_ROWS * FROM foo WHERE b = 1 LIMIT 1000, 10");
$end = microtime(true);
echo $end - $start . "rn";
echo '===== =============MyISAM=======================' . "rn";
$start = microtime(true);
mysql_query("SELECT SQL_NO_CACHE SQL_CALC_FOUND_ROWS * FROM foo2 WHERE b = 1 LIMIT 1000, 10");
$end = microtime(true);
echo $end - $start . "rn";
Return result:
One query can make so much difference! ! InnoDB and MyISAM, quickly analyze why.
First use explain to view
Make sure that no index is used on both sides. The rows queried in the second query, and the query rows of MyISAM are much less than those of InnoDB. On the contrary, the query is slower than InnoDB! ! This Y is a bit strange.
No problem, there is another awesome tool profile
For specific usage, please refer to: http://dev.mysql.com/doc/refman/5.0/en/show-profile.html
How to use it in simple terms:
Mysql > set profiling = 1;
Mysql>show profiles ;
Mysql>show profile for query 1;

You can see from this data that MyISAM’s Sending data is much more time-consuming than InnoDB’s Sending data . View mysql documentation
http://dev.mysql.com/doc/refman/5.0/en/general-thread-states.html
Sending data
The thread is reading and processing rows for a SELECT statement, and sending data to the client. Because operations occurring during this this state tend to perform large amounts of disk access (reads), it is often the longest-running state over the lifetime of a given query.
Sending data is to read the result of the selection from the disk, and then return the result to the client. This process will involve a large number of IO operations. You can use show profile cpu for query XX; to check and find that MyISAM's CPU_system is much larger than InnnoDB. At this point it can be concluded that MyISAM is slower than InnoDB for table queries (different from queries that can be completed using only indexes).

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PHP and Python are both high-level programming languages that are widely used in web development, data processing and automation tasks. 1.PHP is often used to build dynamic websites and content management systems, while Python is often used to build web frameworks and data science. 2.PHP uses echo to output content, Python uses print. 3. Both support object-oriented programming, but the syntax and keywords are different. 4. PHP supports weak type conversion, while Python is more stringent. 5. PHP performance optimization includes using OPcache and asynchronous programming, while Python uses cProfile and asynchronous programming.

PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.

PHP originated in 1994 and was developed by RasmusLerdorf. It was originally used to track website visitors and gradually evolved into a server-side scripting language and was widely used in web development. Python was developed by Guidovan Rossum in the late 1980s and was first released in 1991. It emphasizes code readability and simplicity, and is suitable for scientific computing, data analysis and other fields.

PHP is suitable for web development and rapid prototyping, and Python is suitable for data science and machine learning. 1.PHP is used for dynamic web development, with simple syntax and suitable for rapid development. 2. Python has concise syntax, is suitable for multiple fields, and has a strong library ecosystem.

PHP remains important in the modernization process because it supports a large number of websites and applications and adapts to development needs through frameworks. 1.PHP7 improves performance and introduces new features. 2. Modern frameworks such as Laravel, Symfony and CodeIgniter simplify development and improve code quality. 3. Performance optimization and best practices further improve application efficiency.

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PHP type prompts to improve code quality and readability. 1) Scalar type tips: Since PHP7.0, basic data types are allowed to be specified in function parameters, such as int, float, etc. 2) Return type prompt: Ensure the consistency of the function return value type. 3) Union type prompt: Since PHP8.0, multiple types are allowed to be specified in function parameters or return values. 4) Nullable type prompt: Allows to include null values and handle functions that may return null values.


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