mysql的分頁比較簡單，只需要limit offset,length就可以獲取資料了，但是當offset比較大的時候，mysql明顯效能下降
1.子查詢優化法
mysql> set profiling=1;
query ok, 0 rows affected (0.00 sec)
mysql> select count(*) from member;
| count(*) |
| 169566 |
1 row in set (0.00 sec)
mysql> pager grep !~-
pager set to 'grep !~-'
mysql> select * from member limit 10, 100;
100 rows in set (0.00 sec)
mysql> select * from member where memberid >= (select memberid from member limit 10,1) limit 100;
100 rows in set (0.00 sec)
mysql> select * from member limit 1000, 100;
100 rows in set (0.01 sec)
mysql> select * from member where memberid >= (select memberid from member limit 1000,1) limit 100;
100 rows in set (0.00 sec)
mysql> select * from member limit 100000, 100;
100 rows in set (0.10 sec)
mysql> select * from member where memberid >= (select memberid from member limit 100000,1) limit 100;
100 rows in set (0.02 sec)
mysql> nopager
pager set to stdout
mysql> show profiles/g
*************************** 1. row ***************************
query_id: 1
duration: 0.00003300
query: select count(*) from member
*************************** 2. row ***************************
query_id: 2
duration:0.00167000
query: select * from member limit 10, 100
*************************** 3. row ***************************
query_id: 3
duration: 0.00112400
query: select * from member where memberid >= (select memberid from member limit 10,1) limit 100
*************************** 4. row ***************************
query_id: 4
duration:0.00263200
query: select * from member limit 1000, 100
*************************** 5. row ***************************
query_id: 5
duration:0.00134000
query: select * from member where memberid >= (select memberid from member limit 1000,1) limit 100
*************************** 6. row ***************************
query_id: 6
duration: 0.09956700
query: select * from member limit 100000, 100
*************************** 7. row ***************************
query_id: 7
duration:0.02447700
query: select * from member where memberid >= (select memberid from member limit 100000,1) limit 100
從結果中可以得知，當偏移1000以上使用子查詢法可以有效的提高效能。
但是，子查詢法限制比較大，只能是在沒有where的情況下使用，能用到的機會比較少。可以作為一種思路
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