MySQL選擇百萬條記錄以生成URL

Question

我目前從不同的表格中獲得200萬條記錄，以生成一個用於創建站點地圖的網址。 該腳本占用了太多資源，並占用了100％的服務器性能

詢問

 SELECT CONCAT("/url/profile/id/",u.id,"/",nickname) as url FROM users AS u
    UNION ALL
    Select CONCAT("url/city/", c.id, "/paramId/",p.id,"/",Replace(p.title, " ", "+"),"/",r.region_Name,"/",c.city_Name) AS url
    From city c 
    Join region r On r.id = c.id_region 
    Join country country On country.id = c.id_country
    cross join param p
    Where country.used = 1
    And p.active = 1 

//我將其存儲在$ url_list數組中，然后創建站點地圖..但是這需要時間和大量資源

// i嘗試使用LIMIT 0,50000批量獲取數據，但獲取分頁的最大行需要時間。 代碼也不適合我必須運行兩個具有大數據的查詢

$url_list = array();


$maxrow = SELECT COUNT(*) AS max from (
 SELECT CONCAT("/url/profile/id/",u.id,"/",nickname) as url FROM users AS u
        UNION ALL
        Select CONCAT("url/city/", c.id, "/paramId/",p.id,"/",Replace(p.title, " ", "+"),"/",r.region_Name,"/",c.city_Name) AS url
        From city c 
        Join region r On r.id = c.id_region 
        Join country country On country.id = c.id_country
        cross join param p
        Where country.used = 1
        And p.active = 1) as tmp

$limit = 50,000;
$bybatch = ceil($maxrow/$limit);
$start = 0;
for($i = 0;$i < $bybatch; $i++){
   // run query and store to $result
       (SELECT CONCAT("/url/profile/id/",u.id,"/",nickname) as url FROM users AS u
        UNION ALL
        Select CONCAT("url/city/", c.id, "/paramId/",p.id,"/",Replace(p.title, " ", "+"),"/",r.region_Name,"/",c.city_Name) AS url
        From city c 
        Join region r On r.id = c.id_region 
        Join country country On country.id = c.id_country
        cross join param p
        Where country.used = 1
        And p.active = 1 LIMIT $start,$limit); 

     $start += $limit;
     //push to $url_list
     $url_list = array_push($result);
}

//完成后，我將使用它來創建站點地圖

$linkCount = 1;
        $fileNomb = 1;
        $i = 0;
foreach ($url_list as $ul) { 

            $i += 1; 
            if ($linkCount == 1) {
                $doc  = new DOMDocument('1.0', 'utf-8');
                $doc->formatOutput = true;
                $root = $doc->createElementNS('http://www.sitemaps.org/schemas/sitemap/0.9', 'urlset');
                $doc->appendChild($root);
            }


            $url= $doc->createElement("url");
            $loc= $doc->createElement("loc", $ul['url']); 
            $url->appendChild($loc);
            $priority= $doc->createElement("priority",1); 
            $url->appendChild($priority);


            $root->appendChild($url);

            $linkCount += 1;

            if ($linkCount == 49999) { 
                $f = fopen($this->siteMapMulti . $fileNomb .'.xml', "w");
                fwrite($f,$doc->saveXML());
                fclose($f);

                $linkCount = 1;
                $fileNomb += 1;
            }

        }

還有更好的方法嗎？ 還是要加快性能？

添加

為什么這比sql查詢要快，但卻消耗了100％的服務器資源和性能

$this->db->query('SELECT c.id, c.city_name, r.region_name, cr.country_name FROM city AS c, region AS r, country AS cr  WHERE r.id = c.id_region AND cr.id = c.id_country AND cr.id IN (SELECT id FROM country WHERE use = 1)');

$arrayCity = $this->db->recordsArray(MYSQL_ASSOC);

 $this->db->query('SELECT id, title FROM param WHERE active = 1');

$arrayParam = $this->db->recordsArray(MYSQL_ASSOC);

foreach ($arrayCity as $city) {
        foreach ($arrayParam as $param) {
          $paramTitle = str_replace(' ', '+', $param['title']);
          $url = 'url/city/'. $city['id'] .'/paramId/'. $param['id'] .'/'. $paramTitle .'/'. $city['region_name'] .'/'. $city['city_name'];
          $this->addChild($url);
        }
}

Answer 1

我建議您不要使用UNION而只發出兩個分開的查詢。 它將加速查詢本身。 另外，正如您上面提到的，最好分批獲取數據。

最后，不要收集內存中的所有數據。 立即將其寫入循環中的文件。

只是在開始時打開文件，在循環中寫入每個URL條目，然后在結束時關閉文件。

—打開文件進行寫入

—計數查詢用戶表

—用LIMIT循環進行幾次選擇（如您已經做的那樣）

—就在這里循環， while ($row = mysql_fetch_array())將每一行寫入文件

然后再針對另一張表重復這種算法。 實現將數據寫入文件的功能將很有用，因此您可以調用該功能並遵守DRY原理。