bitsCN.com
看到张宴的博客上关于"http/rest客户端的文章",怎样安装啥的直接都跳过,下面直接进入测试阶段,测试环境:虚拟机
[root@localhost ~]# uname -a
Linux sunss 2.6.18-128.el5 #1 SMP Wed Jan 21 10:44:23 EST 2009 i686 i686 i386 GNU/Linux
内存和交换分区:
[root@localhost ~]# free -m
total used free shared buffers cached
Mem: 376 363 13 0 23 105
-/+ buffers/cache: 233 142
Swap: 1023 133 890
mysql:
[root@localhost ~]# mysql -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or /g.
Your MySQL connection id is 57
Server version: 5.1.26-rc-log Source distribution
Type 'help;' or '/h' for help. Type '/c' to clear the buffer.
mysql>
使用的表结构:
DROP TABLE IF EXISTS `mytable`;
CREATE TABLE `mytable` (
`id` int(10) NOT NULL AUTO_INCREMENT,
`addtime` int(10) NOT NULL,
`title` varchar(255) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
php操作MySQL的程序:
$type = $_GET['type'];
print_r($_GET);
include_once("gettime.php");
$btime = getmicrotime();
$loop_cnt= 1000; //循环次数
$db_host = '127.0.0.1'; //
$db_user = 'sunss'; //
$db_pass = '123456'; //
$db_name = 'test'; //
$db_link = mysql_connect($db_host, $db_user, $db_pass) or die("Connected failed: ".mysql_error()."/n");
mysql_query('set names utf8');
mysql_db_query($db_name, $db_link);
if ("put" == $type) {//修改
$i = 1;
while ($i $title = "jkjkjkjkjkjkjkjkjkjkjkjkjk";
$tt = time();
$sql = "update mytable set addtime=".$tt.",title='".$title."' where id='".$i."'";
$res = mysql_query($sql);
if (FALSE == $res) {
echo "update failed!/n";
}
$i++;
}
} else if ("delete" == $type) { //删除
$i = 1;
while ($i $sql = "delete from mytable where id='".$i."'";
echo "delete sql: ".$sql."
";
$res = mysql_query($sql);
if (FALSE == $res) {
echo "delete failed!/n";
}
$i++;
}
} else if ("post" == $type) { //添加
$i = 0;
while ($i $title = "hahahahahahahahahahahahahahahahahaha";
$tt = time();
$sql = "insert into mytable(addtime, title) values($tt, '".$title."')";
//print "SQL: ".$sql."
";
$res = mysql_query($sql);
if (FALSE == $res) {
echo "insert failed!/n";
}
$i++;
}
}
mysql_close();
$etime = getmicrotime();
$runTime = round($etime - $btime, 4);
echo "runTime: ".$runTime."/r/n
";
?>
单独执行php连接MySQL,单条连接添加1000条记录需要:0.9s左右
php操作memcache的程序:
include_once("gettime.php");
$btime = getmicrotime();
//杩

InnoDB uses redologs and undologs to ensure data consistency and reliability. 1.redologs record data page modification to ensure crash recovery and transaction persistence. 2.undologs records the original data value and supports transaction rollback and MVCC.

Key metrics for EXPLAIN commands include type, key, rows, and Extra. 1) The type reflects the access type of the query. The higher the value, the higher the efficiency, such as const is better than ALL. 2) The key displays the index used, and NULL indicates no index. 3) rows estimates the number of scanned rows, affecting query performance. 4) Extra provides additional information, such as Usingfilesort prompts that it needs to be optimized.

Usingtemporary indicates that the need to create temporary tables in MySQL queries, which are commonly found in ORDERBY using DISTINCT, GROUPBY, or non-indexed columns. You can avoid the occurrence of indexes and rewrite queries and improve query performance. Specifically, when Usingtemporary appears in EXPLAIN output, it means that MySQL needs to create temporary tables to handle queries. This usually occurs when: 1) deduplication or grouping when using DISTINCT or GROUPBY; 2) sort when ORDERBY contains non-index columns; 3) use complex subquery or join operations. Optimization methods include: 1) ORDERBY and GROUPB

MySQL/InnoDB supports four transaction isolation levels: ReadUncommitted, ReadCommitted, RepeatableRead and Serializable. 1.ReadUncommitted allows reading of uncommitted data, which may cause dirty reading. 2. ReadCommitted avoids dirty reading, but non-repeatable reading may occur. 3.RepeatableRead is the default level, avoiding dirty reading and non-repeatable reading, but phantom reading may occur. 4. Serializable avoids all concurrency problems but reduces concurrency. Choosing the appropriate isolation level requires balancing data consistency and performance requirements.

MySQL is suitable for web applications and content management systems and is popular for its open source, high performance and ease of use. 1) Compared with PostgreSQL, MySQL performs better in simple queries and high concurrent read operations. 2) Compared with Oracle, MySQL is more popular among small and medium-sized enterprises because of its open source and low cost. 3) Compared with Microsoft SQL Server, MySQL is more suitable for cross-platform applications. 4) Unlike MongoDB, MySQL is more suitable for structured data and transaction processing.

MySQL index cardinality has a significant impact on query performance: 1. High cardinality index can more effectively narrow the data range and improve query efficiency; 2. Low cardinality index may lead to full table scanning and reduce query performance; 3. In joint index, high cardinality sequences should be placed in front to optimize query.

The MySQL learning path includes basic knowledge, core concepts, usage examples, and optimization techniques. 1) Understand basic concepts such as tables, rows, columns, and SQL queries. 2) Learn the definition, working principles and advantages of MySQL. 3) Master basic CRUD operations and advanced usage, such as indexes and stored procedures. 4) Familiar with common error debugging and performance optimization suggestions, such as rational use of indexes and optimization queries. Through these steps, you will have a full grasp of the use and optimization of MySQL.

MySQL's real-world applications include basic database design and complex query optimization. 1) Basic usage: used to store and manage user data, such as inserting, querying, updating and deleting user information. 2) Advanced usage: Handle complex business logic, such as order and inventory management of e-commerce platforms. 3) Performance optimization: Improve performance by rationally using indexes, partition tables and query caches.


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