優化Mysql UNION查詢以加快加載速度

Question

我是一名初學者，我需要一些幫助來加速以下查詢。在INDEXES中，我也是一名初學者，我不太明白如何添加和使用它們。 如果有人可以請幫助我加快這個查詢，我會深表感謝。 目前查詢花費~10s加載。

顯示行0 - 0（1個總計，查詢花費10.2243秒）

SELECT `location2` AS `location` , '2' AS `number` 
FROM `properties` 
WHERE `price_from` 
BETWEEN 0 
AND 999999 
AND `country` = 'france' 
UNION SELECT `location3` AS `location` , '3' AS `number` 
FROM `properties` 
WHERE `price_from` 
BETWEEN 0 
AND 999999 
AND `location2` = 'france' 
UNION SELECT `location4` AS `location` , '4' AS `number` 
FROM `properties` 
WHERE `price_from` 
BETWEEN 0 
AND 999999 
AND `location3` = 'france' 
UNION SELECT `location5` AS `location` , '5' AS `number` 
FROM `properties` 
WHERE `price_from` 
BETWEEN 0 
AND 999999 
AND `location4` = 'france' 
UNION SELECT `location6` AS `location` , '6' AS `number` 
FROM `properties` 
WHERE `price_from` 
BETWEEN 0 
AND 999999 
AND `location5` = 'france' 

Answer 1

不要張開跨列的陣列。相反，請根據需要製作具有儘可能多行數的另一個表。

通過該更改，您可以避開UNION，我們可以討論如何優化需要的JOIN。