DM7数组索引的概念是什么，相信很多没有经验的人对此束手无策，为此本文总结了问题出现的原因和解决方法，通过这篇文章希望你能解决这个问题。
数组索引指在一个只包含单个数组成员的对象列上创建的索引。
数组索引定义语句
语法格式
CREATE ARRAY INDEX < 索引名> ON [< 模式名>.] < 表名> (< 索引列定义>)
使用说明
1) 暂不支持在水平分区表上创建数组索引；
2) 暂时不支持在有数组索引表上进行批量装载(数组索引失效的例外)；
3) 支持创建数组索引的对象只能包含数组一个成员。数组可以是DM静态数组、动态数组或者ORACLE兼容的嵌套表或VARRAY；
4) 数组项类型只能是可比较的标量类型，不支持复合类型、对象类型或大字段类型；
5) 临时表、垂直分区表不支持；
6) 数组索引不支持改名；
7) 数组索引列不支持改名；
8) 数组索引只能是单索引，不能为组合索引；
9) 不支持空值的检索
10) MPP环境不支持数组索引。
数组索引修改语句
数组索引修改语句与普通索引用法相同，请参考3.7节。与普通索引不同的是，数组索引不支持NOSORT和ONLINE用法。
数组索引使用
使用数组索引进行查询，必须使用谓词CONTAINS。
语法格式
CONTAINS(< 索引列名>,)
或者
CONTAINS(< 索引列名>,arr_var_exp)
参数
val：必须为与对象列数组项相同或可转换的标量类型表达式。
arr_var_exp：必须为数组类型（DM静态数组、动态数组或者ORACLE兼容的嵌套表或VARRAY），其数组项类型必须与对象列数组项类型相同或可转换。
举例说明
SQL> CREATE TYPE ARR_NUM1 IS VARRAY(1024) OF NUMBER; --VARRAY数组
2 /
executed successfully
used time: 17.012(ms). Execute id is 81.
SQL> CREATE TYPE ARR_NUM2 IS TABLE OF NUMBER; --嵌套表
2 /
executed successfully
used time: 11.795(ms). Execute id is 82.
SQL> CREATE TYPE ARR_NUM3 IS ARRAY NUMBER[]; --动态
2 /
executed successfully
used time: 14.784(ms). Execute id is 83.
SQL> CREATE TYPE ARR_NUM4 IS ARRAY NUMBER[3]; --静态
2 /
executed successfully
used time: 14.017(ms). Execute id is 84.
SQL> CREATE CLASS CLS1 AS V ARR_NUM1;END;
2 /
executed successfully
used time: 12.893(ms). Execute id is 85.
SQL> CREATE TABLE TEST (C1 CLS1);
executed successfully
used time: 16.078(ms). Execute id is 87.
SQL> INSERT INTO TEST VALUES(CLS1(ARR_NUM1(1,2,3)));
affect rows 1
used time: 1.537(ms). Execute id is 88.
SQL> INSERT INTO TEST VALUES(CLS1(ARR_NUM1(1,2)));
affect rows 1
used time: 1.074(ms). Execute id is 89.
SQL> INSERT INTO TEST VALUES(CLS1(ARR_NUM1(2,1)));
affect rows 1
used time: 1.149(ms). Execute id is 90.
SQL> INSERT INTO TEST VALUES(CLS1(ARR_NUM1(1,5)));
affect rows 1
used time: 1.110(ms). Execute id is 91.
SQL> INSERT INTO TEST VALUES(CLS1(ARR_NUM1(2,4)));
affect rows 1
used time: 1.068(ms). Execute id is 92.
SQL> INSERT INTO TEST VALUES(CLS1(ARR_NUM1(4,5,6)));
affect rows 1
used time: 1.152(ms). Execute id is 93.
SQL> commit;
executed successfully
used time: 17.231(ms). Execute id is 94.
SQL> select * from test;
LINEID C1
---------- ------------------------
1 JY.CLS1(ARR_NUM1(1,2,3))
2 JY.CLS1(ARR_NUM1(1,2))
3 JY.CLS1(ARR_NUM1(2,1))
4 JY.CLS1(ARR_NUM1(1,5))
5 JY.CLS1(ARR_NUM1(2,4))
6 JY.CLS1(ARR_NUM1(4,5,6))
6 rows got
used time: 1.063(ms). Execute id is 95.
SQL> CREATE ARRAY INDEX IDX ON TEST(C1); --创建数组索引
2 /
executed successfully
used time: 20.879(ms). Execute id is 97.
SQL> SELECT * FROM TEST WHERE CONTAINS(C1,1,2,3); --使用数组索引查询
2 /
LINEID C1
---------- ------------------------
1 JY.CLS1(ARR_NUM1(1,2,3))
2 JY.CLS1(ARR_NUM1(1,2))
3 JY.CLS1(ARR_NUM1(2,1))
4 JY.CLS1(ARR_NUM1(1,5))
5 JY.CLS1(ARR_NUM1(2,4))
used time: 3.400(ms). Execute id is 98.
SQL> --嵌套表
2 DECLARE
3 X ARR_NUM2;
4 BEGIN
5 X := ARR_NUM2();
6 X.EXTEND(3);
7 X(1) := 1;
8 X(2) := 2;
9 X(3) := 3;
10 SELECT * FROM TEST WHERE CONTAINS(C1,X);
11 END;
12 /
LINEID C1
---------- ------------------------
1 JY.CLS1(ARR_NUM1(1,2,3))
2 JY.CLS1(ARR_NUM1(1,5))
3 JY.CLS1(ARR_NUM1(2,1))
4 JY.CLS1(ARR_NUM1(1,2))
5 JY.CLS1(ARR_NUM1(2,4))
used time: 7.179(ms). Execute id is 100.
SQL> --动态数组
2 DECLARE
3 X ARR_NUM3;
4 BEGIN
5 X := NEW NUMBER [3];
6 X[1]:= 1;
7 X[2]:= 2;
8 X[3]:= 3;
9 SELECT * FROM TEST WHERE CONTAINS(C1,X);
10 END;
11 /
LINEID C1
---------- ------------------------
1 JY.CLS1(ARR_NUM1(1,2,3))
2 JY.CLS1(ARR_NUM1(1,5))
3 JY.CLS1(ARR_NUM1(2,1))
4 JY.CLS1(ARR_NUM1(1,2))
5 JY.CLS1(ARR_NUM1(2,4))
used time: 6.016(ms). Execute id is 102.
SQL> --静态数组
2 DECLARE
3 X ARR_NUM4;
4 BEGIN
5 X[1]:= 1;
6 X[2]:= 2;
7 X[3]:= 3;
8 SELECT * FROM TEST WHERE CONTAINS(C1,X);
9 END;
10 /
LINEID C1
---------- ------------------------
1 JY.CLS1(ARR_NUM1(1,2,3))
2 JY.CLS1(ARR_NUM1(1,5))
3 JY.CLS1(ARR_NUM1(2,1))
4 JY.CLS1(ARR_NUM1(1,2))
5 JY.CLS1(ARR_NUM1(2,4))
used time: 5.688(ms). Execute id is 104.数组索引删除语句
数组索引删除语句与普通索引用法相同
SQL> drop index idx;
executed successfully
used time: 402.153(ms). Execute id is 106.
SQL> SELECT * FROM TEST WHERE CONTAINS(C1,1,2,3);
SELECT * FROM TEST WHERE CONTAINS(C1,1,2,3);
[-3252]:Error in line: 1
The array index is not created on the column[C1].
used time: 1.016(ms). Execute id is 0.看完上述内容，你们掌握DM7数组索引的概念是什么的方法了吗？如果还想学到更多技能或想了解更多相关内容，欢迎关注亿速云行业资讯频道，感谢各位的阅读！
