select customer_id,title,content from `product_comment` where audit_status=1 and product_id=100 limit 0,5;
鐩墠鍙互瀵箂elect update insert replace delete 杩涜鍒嗘瀽
鍙互浠巈xplain鐭ラ亾
– sql濡備綍浣跨敤绱㈠紩
– 鑱旀帴鏌ヨ鐨勬墽琛岄『搴
– 鏌ヨ鎵弿鐨勬暟鎹鏁
渚嬪锛
id锛1
select_type:simple
table: product_comment
partitions: null
type: all
possible_keys: null
key: null
key_len:null
ref:null
rows:9494
filtered:1.00
extra:using where
id鍒椾腑鐨勬暟鎹负涓缁勬暟瀛楋紝琛ㄧず鎵цselect璇彞鐨勯『搴
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id鍊艰秺澶т紭鍏堢骇瓒婇珮锛岃秺鍏堣鎵ц
| 鍊 | 鍚箟 |
|---|---|
| SIMPLE | 涓嶅寘鍚瓙鏌ヨ鎴栨槸UNION鎿嶄綔鐨勬煡璇 |
| primary | 鏌ヨ涓鏋滃寘鍚换浣曞瓙鏌ヨ锛岄偅涔堟渶澶栧眰鐨勬煡璇㈠垯琚爣璁颁负primary |
| subquery | select 鍒楄〃涓殑瀛愭煡璇 |
| dependent subquery | 渚濊禆澶栭儴缁撴灉鐨勫瓙鏌ヨ |
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| 鎬ц兘 | 鍊 | 鍚箟 |
|---|---|---|
| 楂 | system | 杩欐槸const杩炴帴绫诲瀷鐨勪竴涓壒渚嬶紝褰撴煡璇㈢殑琛ㄥ彧鏈変竴琛屾椂浣跨敤 |
| const | 琛ㄤ腑鏈変笖鍙湁涓涓尮閰嶇殑琛屾椂浣跨敤锛屽瀵逛富閿垨鏄敮涓绱㈠紩鐨勬煡璇紝杩欐槸鏁堢巼鏈楂樼殑杩炴帴鏂瑰紡 | |
| eq_ref | 鍞竴绱㈠紩鎴栬呬富閿储寮曟煡鎵撅紝瀵逛簬姣忎釜绱㈠紩閿紝琛ㄤ腑鍙湁涓鏉¤褰曚笌涔嬪尮閰嶃 | |
| ref | 闈炲敮涓绱㈠紩鏌ユ壘锛岃繑鍥炲尮閰嶆煇涓崟鐙兼墍鏈夎銆 | |
| ref_or_null | 绫诲瀷浜巖ef绫诲瀷鐨勬煡璇紝浣嗘槸闄勫姞浜嗗null鍊煎垪鐨勬煡璇 | |
| index_merge | 璇ヨ繛鎺ョ被鍨嬭〃绀轰娇鐢ㄤ簡绱㈠紩鍚堝苟浼樺寲鏂规硶銆 | |
| range | 绱㈠紩鑼冨洿鎵弿锛屽父瑙佷簬between锛> , <杩欐牱鐨勬煡璇㈡潯浠 | |
| index | FUll index scan鍏ㄧ储寮曟壂鎻忥紝鍚宎ll鐨勫尯鍒槸锛岄亶鍘嗙殑鏄储寮曟爲 | |
| 浣 | all | full table scan 鍏ㄨ〃鎵弿锛 鏁堢巼鏈宸 |
| 鍊 | 鍚箟 |
|---|---|
| distanct | 浼樺寲distinct鎿嶄綔锛屽湪鎵惧埌绗竴鍖归厤鐨勫厓缁勫悗鍗冲仠姝㈡壘鍚屾牱鍊肩殑鍔ㄤ綔 |
| not exists | 浣跨敤not exists鏉ヤ紭鍖栨煡璇 |
| using filesort | 浣跨敤棰濆鎿嶄綔杩涜鎺掑簭锛岄氬父浼氬嚭鐜板湪 order by 鎴杇roup by 鏌ヨ涓 |
| using index | 浣跨敤浜嗚鐩栫储寮曡繘琛屾煡璇 |
| using temporary | MySQL闇瑕佷娇鐢ㄤ复鏃惰〃鏉ュ鐞嗘煡璇紝甯歌浜庢帓搴忥紝瀛愭煡璇㈠拰鍒嗙粍鏌ヨ |
| using where | 闇瑕佸湪MySQL鏈嶅姟鍣ㄥ眰浣跨敤where 鏉′欢鏉ヨ繃婊ゆ暟鎹 |
| select tables optimized away | 鐩存帴閫氳繃绱㈠紩鏉ヨ幏寰楁暟鎹紝涓嶇敤璁块棶琛 |
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