mysql数据库查询优化 mysql效率第1/3页

提高MySQL 查询效率的三个技巧小结
MySQL由于它本身的小巧和操作的高效, 在数据库应用中越来越多的被采用.我在开发一个P2P应用的时候曾经使用MySQL来保存P2P节点,由于P2P的应用中,结点数动辄上万个,而且节点变化频繁,因此一定要保持查询和插入的高效.以下是我在使用过程中做的提高效率的三个有效的尝试.

l 使用statement进行绑定查询
使用statement可以提前构建查询语法树,在查询时不再需要构建语法树就直接查询.因此可以很好的提高查询的效率. 这个方法适合于查询条件固定但查询非常频繁的场合.
使用方法是:
绑定, 创建一个MYSQL_STMT变量,与对应的查询字符串绑定,字符串中的问号代表要传入的变量,每个问号都必须指定一个变量.
查询, 输入每个指定的变量, 传入MYSQL_STMT变量用可用的连接句柄执行.
代码如下:

//1.绑定  
bool CDBManager::BindInsertStmt(MYSQL * connecthandle)  
{  
       //作插入操作的绑定  
       MYSQL_BIND insertbind[FEILD_NUM];  
       if(m_stInsertParam == NULL)  
              m_stInsertParam = new CHostCacheTable;  
       m_stInsertStmt = mysql_stmt_init(connecthandle);  
       //构建绑定字符串  
       char insertSQL[SQL_LENGTH];  
       strcpy(insertSQL, "insert into HostCache(SessionID, ChannelID, ISPType, "  
              "ExternalIP, ExternalPort, InternalIP, InternalPort) "  
              "values(?, ?, ?, ?, ?, ?, ?)");  
       mysql_stmt_prepare(m_stInsertStmt, insertSQL, strlen(insertSQL));  
       int param_count= mysql_stmt_param_count(m_stInsertStmt);  
       if(param_count != FEILD_NUM)  
              return false;  
       //填充bind结构数组, m_sInsertParam是这个statement关联的结构变量  
       memset(insertbind, 0, sizeof(insertbind));  
       insertbind[0].buffer_type = MYSQL_TYPE_STRING;  
       insertbind[0].buffer_length = ID_LENGTH /* -1 */;  
       insertbind[0].buffer = (char *)m_stInsertParam->sessionid;  
       insertbind[0].is_null = 0;  
       insertbind[0].length = 0;  

       insertbind[1].buffer_type = MYSQL_TYPE_STRING;  
       insertbind[1].buffer_length = ID_LENGTH /* -1 */;  
       insertbind[1].buffer = (char *)m_stInsertParam->channelid;  
       insertbind[1].is_null = 0;  
       insertbind[1].length = 0;  

       insertbind[2].buffer_type = MYSQL_TYPE_TINY;  
       insertbind[2].buffer = (char *)&m_stInsertParam->ISPtype;  
       insertbind[2].is_null = 0;  
       insertbind[2].length = 0;  

       insertbind[3].buffer_type = MYSQL_TYPE_LONG;  
       insertbind[3].buffer = (char *)&m_stInsertParam->externalIP;  
       insertbind[3].is_null = 0;  
       insertbind[3].length = 0;  

       insertbind[4].buffer_type = MYSQL_TYPE_SHORT;  
       insertbind[4].buffer = (char *)&m_stInsertParam->externalPort;  
       insertbind[4].is_null = 0;  
       insertbind[4].length = 0;  

       insertbind[5].buffer_type = MYSQL_TYPE_LONG;  
       insertbind[5].buffer = (char *)&m_stInsertParam->internalIP;  
       insertbind[5].is_null = 0;  
       insertbind[5].length = 0;  

       insertbind[6].buffer_type = MYSQL_TYPE_SHORT;  
       insertbind[6].buffer = (char *)&m_stInsertParam->internalPort;  
       insertbind[6].is_null = 0;  
       insertbind[6].is_null = 0;  
       //绑定  
       if (mysql_stmt_bind_param(m_stInsertStmt, insertbind))  
              return false;  
       return true;  
}  

//2.查询  
bool CDBManager::InsertHostCache2(MYSQL * connecthandle, char * sessionid, char * channelid, int ISPtype,   
              unsigned int eIP, unsigned short eport, unsigned int iIP, unsigned short iport)  
{  
       //填充结构变量m_sInsertParam  
       strcpy(m_stInsertParam->sessionid, sessionid);  
       strcpy(m_stInsertParam->channelid, channelid);  
       m_stInsertParam->ISPtype = ISPtype;  
       m_stInsertParam->externalIP = eIP;  
       m_stInsertParam->externalPort = eport;  
       m_stInsertParam->internalIP = iIP;  
       m_stInsertParam->internalPort = iport;  
       //执行statement,性能瓶颈处  
       if(mysql_stmt_execute(m_stInsertStmt))  
              return false;  
       return true;  
}