DM7数组索引的概念是什么

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 successfullyused time: 17.012(ms). Execute id is 81.SQL> CREATE TYPE ARR_NUM2 IS TABLE OF NUMBER; --嵌套表2   /executed successfullyused time: 11.795(ms). Execute id is 82.SQL> CREATE TYPE ARR_NUM3 IS ARRAY NUMBER[]; --动态2   /executed successfullyused time: 14.784(ms). Execute id is 83.SQL> CREATE TYPE ARR_NUM4 IS ARRAY NUMBER[3]; --静态2   /executed successfullyused time: 14.017(ms). Execute id is 84.SQL> CREATE CLASS CLS1 AS V ARR_NUM1;END;2   /executed successfullyused time: 12.893(ms). Execute id is 85.SQL> CREATE TABLE TEST (C1 CLS1);executed successfullyused time: 16.078(ms). Execute id is 87.SQL> INSERT INTO TEST VALUES(CLS1(ARR_NUM1(1,2,3)));affect rows 1used time: 1.537(ms). Execute id is 88.SQL> INSERT INTO TEST VALUES(CLS1(ARR_NUM1(1,2)));affect rows 1used time: 1.074(ms). Execute id is 89.SQL> INSERT INTO TEST VALUES(CLS1(ARR_NUM1(2,1)));affect rows 1used time: 1.149(ms). Execute id is 90.SQL> INSERT INTO TEST VALUES(CLS1(ARR_NUM1(1,5)));affect rows 1used time: 1.110(ms). Execute id is 91.SQL> INSERT INTO TEST VALUES(CLS1(ARR_NUM1(2,4)));affect rows 1used time: 1.068(ms). Execute id is 92.SQL> INSERT INTO TEST VALUES(CLS1(ARR_NUM1(4,5,6)));affect rows 1used time: 1.152(ms). Execute id is 93.SQL> commit;executed successfullyused 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 gotused time: 1.063(ms). Execute id is 95.SQL> CREATE ARRAY INDEX IDX ON TEST(C1); --创建数组索引2   /executed successfullyused 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   DECLARE3   X ARR_NUM2;4   BEGIN5   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   DECLARE3   X ARR_NUM3;4   BEGIN5   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   DECLARE3   X ARR_NUM4;4   BEGIN5   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 successfullyused 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: 1The array index is not created on the column[C1].used time: 1.016(ms). Execute id is 0.

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