Informix索引性能调优的建议-Mysql Tutorial-php.cn

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Informix索引性能调优的建议

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Jun 07, 2016 pm 05:16 PM

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索引性能：1、对于类似char（100）这样的字段不要设计为index2、Index的字段个数不要超过3个3、Index上也会加锁，所以会造成新的

索引性能：

1、对于类似char（100）这样的字段不要设计为index

2、Index的字段个数不要超过3个

3、Index上也会加锁，所以会造成新的锁的性能问题

4、Index尽量不避免使用，index是用的空间换取的性能方式，即使查询加速了也会导致insert等DML操作变慢

5、Index中的使用的字段的顺序有讲究，不要随意

6、静态表数据不发生变换的表最多index个数不要超过5-8个

7、OLTP系统业务操作表创建2-5个索引

8、OLAP系统可以创建5-8个索引

9、哪些字段建立索引，where条件中的才可以建索引，表关联的groupby，orderby可以建索引，但是对于交易性的系统中的orderby不要建索引，要根据实际情况，要看结果记录有多少，如果比较少，比如几千条以内不要建索引

10、索引中的字段比如C1有103个，C2有2个不同的值，C3有100个，那么C2就不要作为字段

11、避免建复合索引的情况是大字段，C2建立后记录数和C2前记录数相差很少的时候也不需要建立索引

12、避免使用like，避免索引列上使用函数，避免索引上使用is null或is not null，，避免使用!=

13、避免改变索引列的类型，避免使用having子句

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