三個技巧提高MySQL查詢效率

MySQL由於它本身的小巧和操作的高效, 在數據庫應用中越來越多的被采用.我在開發一個P2P應用的時候曾經使用MySQL來保存P2P節點,由於P2P的應用中,結點數動辄上萬個,而且節點變化頻繁,因此一定要保持查詢和插入的高效.以下是我在使用過程中做的提高效率的三個有效的嘗試.

1、使用statement進行綁定查詢

使用statement可以提前構建查詢語法樹,在查詢時不再需要構建語法樹就直接查詢.因此可以很好的提高查詢的效率. 這個方法適合於查詢條件固定但查詢非常頻繁的場合.

使用方法是：

綁定, 創建一個MySQL_STMT變量,與對應的查詢字符串綁定,字符串中的問號代表要傳入的變量,每個問號都必須指定一個變量.
查詢, 輸入每個指定的變量, 傳入MySQL_STMT變量用可用的連接句柄執行.

代碼如下：

//1.綁定
bool CDBManager::BindInsertStmt(MySQL * connecthandle)
{
       //作插入操作的綁定
       MySQL_BIND insertbind[FEILD_NUM];
       if(m_stInsertParam == NULL)
              m_stInsertParam = new CHostCacheTable;
       m_stInsertStmt = MySQL_stmt_init(connecthandle);
       //構建綁定字符串
       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結構數組, m_sInsertParam是這個statement關聯的結構變量
       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;
       //綁定
       if (MySQL_stmt_bind_param(m_stInsertStmt, insertbind))
              return false;

      return true;
}

//2.查詢
bool CDBManager::InsertHostCache2(MySQL * connecthandle, char * sessionid, char * channelid, int ISPtype, \
              unsigned int eIP, unsigned short eport, unsigned int iIP, unsigned short iport)
{
       //填充結構變量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;
       //執行statement,性能瓶頸處
       if(MySQL_stmt_execute(m_stInsertStmt))
              return false;
       return true;
}