MySQL LIKE vs LOCATE

Question

有谁知道哪一个更快：

SELECT * FROM table WHERE column LIKE '%text%';

或

SELECT * FROM table WHERE LOCATE('text',column)>0;

Answer 1

2015年4月20日新增：请同时阅读下面的Hallie's answer

---

第一个但很少。主要是因为它不需要进行额外的> 0比较。

mysql> SELECT BENCHMARK(100000000,LOCATE('foo','foobar'));
+---------------------------------------------+
| BENCHMARK(100000000,LOCATE('foo','foobar')) |
+---------------------------------------------+
|                                           0 |
+---------------------------------------------+
1 row in set (3.24 sec)

mysql> SELECT BENCHMARK(100000000,LOCATE('foo','foobar') > 0);
+-------------------------------------------------+
| BENCHMARK(100000000,LOCATE('foo','foobar') > 0) |
+-------------------------------------------------+
|                                               0 |
+-------------------------------------------------+
1 row in set (4.63 sec)


mysql> SELECT BENCHMARK(100000000,'foobar' LIKE '%foo%');
+--------------------------------------------+
| BENCHMARK(100000000,'foobar' LIKE '%foo%') |
+--------------------------------------------+
|                                          0 |
+--------------------------------------------+
1 row in set (4.28 sec)


mysql> SELECT @@version;
+----------------------+
| @@version            |
+----------------------+
| 5.1.36-community-log |
+----------------------+
1 row in set (0.01 sec)

Answer 2

+1 @Mchl最直接回答问题。

但我们应该记住，这两种解决方案都不能使用索引，因此他们必须进行表扫描。

当你试图修补泰坦尼克号的船体时，试图在布或塑料胶粘绷带之间做出决定是有点傻。

对于此类查询，需要full-text search index。根据表格的大小，这将是hundreds or thousands of times faster。

Answer 3

我做了一些测试，因为Mchi做了。我认为很难说哪一个更快。它看起来取决于第一次出现的子串。

mysql> select benchmark(100000000, 'afoobar' like '%foo%');
+----------------------------------------------+
| benchmark(100000000, 'afoobar' like '%foo%') |
+----------------------------------------------+
|                                            0 |
+----------------------------------------------+
1 row in set (9.80 sec)

mysql> select benchmark(100000000, locate('foo', 'afoobar'));
+------------------------------------------------+
| benchmark(100000000, locate('foo', 'afoobar')) |
+------------------------------------------------+
|                                              0 |
+------------------------------------------------+
1 row in set (8.08 sec)

mysql> select benchmark(100000000, 'abfoobar' like '%foo%');
+-----------------------------------------------+
| benchmark(100000000, 'abfoobar' like '%foo%') |
+-----------------------------------------------+
|                                             0 |
+-----------------------------------------------+
1 row in set (10.55 sec)

mysql> select benchmark(100000000, locate('foo', 'abfoobar'));
+-------------------------------------------------+
| benchmark(100000000, locate('foo', 'abfoobar')) |
+-------------------------------------------------+
|                                               0 |
+-------------------------------------------------+
1 row in set (10.63 sec)

mysql> select benchmark(100000000, 'abcfoobar' like '%foo%');
+------------------------------------------------+
| benchmark(100000000, 'abcfoobar' like '%foo%') |
+------------------------------------------------+
|                                              0 |
+------------------------------------------------+
1 row in set (11.54 sec)

mysql> select benchmark(100000000, locate('foo', 'abcfoobar'));
+--------------------------------------------------+
| benchmark(100000000, locate('foo', 'abcfoobar')) |
+--------------------------------------------------+
|                                                0 |
+--------------------------------------------------+
1 row in set (12.48 sec)

mysql> select @@version;
+------------+
| @@version  |
+------------+
| 5.5.27-log |
+------------+
1 row in set (0.01 sec)