如何使用 oracle 文本索引从 json 中提取数据答案

【问题标题】：how to extract data from json using oracle text index如何使用 oracle 文本索引从 json 中提取数据
【发布时间】：2017-10-29 21:23:14
【问题描述】：

我有一个表，它有一个 Oracle 文本索引。我创建了索引，因为我需要一个额外的快速搜索。该表包含 JSON 数据。 Oracle json_textcontains 工作得非常糟糕，所以我尝试使用 CONTAINS（如果我们查看查询计划，json_textcontains 实际上会被重写为 CONTAINS）。

我想通过给定的 class_type 和 id 的值来查找所有 json，但 Oracle 查找整个 JSON，而不认为 class_type 和 id 应该在一个 JSON 部分中，即它处理 JSON 不像结构化数据，而是像一个巨大的字符串。

格式良好的 JSON 如下所示：

{
     "class":[
              {
               "class_type":"ownership",
               "values":[{"nm":"id","value":"1"}]
              },
              {
               "class_type":"country",
               "values":[{"nm":"id","value":"640"}]
              },
              ,
              {
               "class_type":"features",
               "values":[{"nm":"id","value":"15"},{"nm":"id","value":"20"}]
              }
             ]
    }

不应该找到的第二个看起来像这样：

{
     "class":[
              {
               "class_type":"ownership",
               "values":[{"nm":"id","value":"18"}]
              },
              {
               "class_type":"country",
               "values":[{"nm":"id","value":"11"}]
              },
              ,
              {
               "class_type":"features",
               "values":[{"nm":"id","value":"7"},{"nm":"id","value":"640"}]
              }
             ]
    }

请查看如何重现我想要实现的目标：

create table perso.json_data(id number, data_val blob);

insert into perso.json_data 

values(
1,
utl_raw.cast_to_raw('{"class":[{"class_type":"ownership","values":[{"nm":"id","value":"1"}]},{"class_type":"country","values":[{"nm":"id","value":"640"}]},{"class_type":"features","values":[{"nm":"id","value":"15"},{"nm":"id","value":"20"}]}]}')
);


insert into perso.json_data values(
2,
utl_raw.cast_to_raw('{"class":[{"class_type":"ownership","values":[{"nm":"id","value":"18"}]},{"class_type":"country","values":[{"nm":"id","value":"11"}]},{"class_type":"features","values":[{"nm":"id","value":"7"},{"nm":"id","value":"640"}]}]}')
)
;

commit;


ALTER TABLE perso.json_data
ADD CONSTRAINT check_is_json
 CHECK (data_val IS JSON (STRICT));

 CREATE INDEX perso.json_data_idx ON json_data (data_val)
 INDEXTYPE IS CTXSYS.CONTEXT
 PARAMETERS ('section group CTXSYS.JSON_SECTION_GROUP SYNC (ON COMMIT)');


select *
from perso.json_data

where ctxsys.contains(data_val, '(640 INPATH(/class/values/value)) and (country inpath (/class/class_type))')>0

查询返回 2 行，但我希望只获得 id = 1 的记录。

如何在不使用 JSON_TABLE 的情况下使用具有搜索功能的全文索引而不出现我突出显示的错误？

没有以关系格式放置数据的选项。

提前致谢。

【问题讨论】：

标签： json oracle

【解决方案1】：

请不要直接使用文本索引来尝试解决此类问题。这不是它的设计目的..

在 12.2.0.1.0 中，这应该对您有用（是的，它确实使用了专门版本的文本索引，但它也应用选择性后过滤以确保结果正确）..

SQL> create table json_data(id number, data_val blob)
  2  /

Table created.

SQL> insert into json_data values(
  2    1,utl_raw.cast_to_raw('{"class":[{"class_type":"ownership","values":[{"nm":"id","value":"1"}]},{"class_type":"cou
ntry","values":[{"nm":"id","value":"640"}]},{"class_type":"features","values":[{"nm":"id","value":"15"},{"nm":"id","valu
e":"20"}]}]}')
  3  )
  4  /

1 row created.


Execution Plan
----------------------------------------------------------

--------------------------------------------------------------------------------------
| Id  | Operation                | Name      | Rows  | Bytes | Cost (%CPU)| Time     |
--------------------------------------------------------------------------------------
|   0 | INSERT STATEMENT         |           |     1 |   100 |     1   (0)| 00:00:01 |
|   1 |  LOAD TABLE CONVENTIONAL | JSON_DATA |       |       |            |          |
--------------------------------------------------------------------------------------

SQL> insert into json_data values(
  2    2,utl_raw.cast_to_raw('{"class":[{"class_type":"ownership","values":[{"nm":"id","value":"18"}]},{"class_type":"co
untry","values":[{"nm":"id","value":"11"}]},{"class_type":"features","values":[{"nm":"id","value":"7"},{"nm":"id","value
":"640"}]}]}')
  3  )
  4  /

1 row created.


Execution Plan
----------------------------------------------------------

--------------------------------------------------------------------------------------
| Id  | Operation                | Name      | Rows  | Bytes | Cost (%CPU)| Time     |
--------------------------------------------------------------------------------------
|   0 | INSERT STATEMENT         |           |     1 |   100 |     1   (0)| 00:00:01 |
|   1 |  LOAD TABLE CONVENTIONAL | JSON_DATA |       |       |            |          |
--------------------------------------------------------------------------------------

SQL> commit
  2  /

Commit complete.

SQL> ALTER TABLE json_data
  2  ADD CONSTRAINT check_is_json
  3   CHECK (data_val IS JSON (STRICT))
  4  /

Table altered.

SQL> CREATE SEARCH INDEX json_SEARCH_idx ON json_data (data_val) for JSON
  2  /

Index created.

SQL> set autotrace on explain
SQL> --
SQL> set lines 256 trimspool on pages 50
SQL> --
SQL> select ID, json_query(data_val, '$' PRETTY)
  2    from JSON_DATA
  3  /

        ID
----------
JSON_QUERY(DATA_VAL,'$'PRETTY)
------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------
----------------
         1
{
  "class" :
  [
    {
      "class_type" : "ownership",
      "values" :
      [
        {
          "nm" : "id",
          "value" : "1"
        }
      ]
    },
    {
      "class_type" : "country",
      "values" :
      [
        {
          "nm" : "id",
          "value" : "640"
        }
      ]
    },
    {
      "class_type" : "features",
      "values" :
      [
        {
          "nm" : "id",
          "value" : "15"
        },
        {
          "nm" : "id",
          "value" : "20"
        }
      ]
    }
  ]
}

         2
{
  "class" :
  [

        ID
----------
JSON_QUERY(DATA_VAL,'$'PRETTY)
------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------
----------------
    {
      "class_type" : "ownership",
      "values" :
      [
        {
          "nm" : "id",
          "value" : "18"
        }
      ]
    },
    {
      "class_type" : "country",
      "values" :
      [
        {
          "nm" : "id",
          "value" : "11"
        }
      ]
    },
    {
      "class_type" : "features",
      "values" :
      [
        {
          "nm" : "id",
          "value" : "7"
        },
        {
          "nm" : "id",
          "value" : "640"
        }
      ]
    }
  ]
}



Execution Plan
----------------------------------------------------------
Plan hash value: 3213740116

-------------------------------------------------------------------------------
| Id  | Operation         | Name      | Rows  | Bytes | Cost (%CPU)| Time     |
-------------------------------------------------------------------------------
|   0 | SELECT STATEMENT  |           |     2 |  4030 |     3   (0)| 00:00:01 |
|   1 |  TABLE ACCESS FULL| JSON_DATA |     2 |  4030 |     3   (0)| 00:00:01 |
-------------------------------------------------------------------------------

Note
-----
   - dynamic statistics used: dynamic sampling (level=2)

SQL> select ID, to_clob(data_val)
  2    from json_data
  3   where JSON_EXISTS(data_val,'$?(exists(@.class?(@.values.value == $VALUE && @.class_type == $TYPE)))' passing '640'
 as "VALUE", 'country' as "TYPE")
  4  /

        ID TO_CLOB(DATA_VAL)
---------- --------------------------------------------------------------------------------
         1 {"class":[{"class_type":"ownership","values":[{"nm":"id","value":"1"}]},{"class_
           type":"country","values":[{"nm":"id","value":"640"}]},{"class_type":"features","
           values":[{"nm":"id","value":"15"},{"nm":"id","value":"20"}]}]}



Execution Plan
----------------------------------------------------------
Plan hash value: 3248304200

-----------------------------------------------------------------------------------------------
| Id  | Operation                   | Name            | Rows  | Bytes | Cost (%CPU)| Time     |
-----------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |                 |     1 |  2027 |     4   (0)| 00:00:01 |
|*  1 |  TABLE ACCESS BY INDEX ROWID| JSON_DATA       |     1 |  2027 |     4   (0)| 00:00:01 |
|*  2 |   DOMAIN INDEX              | JSON_SEARCH_IDX |       |       |     4   (0)| 00:00:01 |
-----------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   1 - filter(JSON_EXISTS2("DATA_VAL" FORMAT JSON , '$?(exists(@.class?(@.values.value
              == $VALUE && @.class_type == $TYPE)))' PASSING '640' AS "VALUE" , 'country' AS "TYPE"
              FALSE ON ERROR)=1)
   2 - access("CTXSYS"."CONTAINS"("JSON_DATA"."DATA_VAL",'{640} INPATH
              (/class/values/value) and {country} INPATH (/class/class_type)')>0)

Note
-----
   - dynamic statistics used: dynamic sampling (level=2)

SQL> select ID, TO_CLOB(DATA_VAL)
  2    from JSON_DATA d
  3   where exists (
  4           select 1
  5             from JSON_TABLE(
  6                    data_val,
  7                    '$.class'
  8                    columns (
  9                      CLASS_TYPE VARCHAR2(32) PATH '$.class_type',
 10                      NESTED PATH '$.values.value'
 11                      columns (
 12                        "VALUE"  VARCHAR2(32) path '$'
 13                      )
 14                    )
 15                  )
 16            where CLASS_TYPE = 'country' and "VALUE" = '640'
 17        )
 18  /

        ID TO_CLOB(DATA_VAL)
---------- --------------------------------------------------------------------------------
         1 {"class":[{"class_type":"ownership","values":[{"nm":"id","value":"1"}]},{"class_
           type":"country","values":[{"nm":"id","value":"640"}]},{"class_type":"features","
           values":[{"nm":"id","value":"15"},{"nm":"id","value":"20"}]}]}



Execution Plan
----------------------------------------------------------
Plan hash value: 1621266031

-------------------------------------------------------------------------------------
| Id  | Operation               | Name      | Rows  | Bytes | Cost (%CPU)| Time     |
-------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT        |           |     1 |  2027 |    32   (0)| 00:00:01 |
|*  1 |  FILTER                 |           |       |       |            |          |
|   2 |   TABLE ACCESS FULL     | JSON_DATA |     2 |  4054 |     3   (0)| 00:00:01 |
|*  3 |   FILTER                |           |       |       |            |          |
|*  4 |    JSONTABLE EVALUATION |           |       |       |            |          |
-------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   1 - filter( EXISTS (SELECT 0 FROM JSON_TABLE( :B1, '$.class' COLUMNS(
              "CLASS_TYPE" VARCHAR2(32) PATH '$.class_type' NULL ON ERROR , NESTED PATH
              '$.values.value' COLUMNS( "VALUE" VARCHAR2(32) PATH '$' NULL ON ERROR ) ) )
              "P" WHERE "CTXSYS"."CONTAINS"(:B2,'({country} INPATH (/class/class_type))
              and ({640} INPATH (/class/values/value))')>0 AND "P"."CLASS_TYPE"='country'
              AND "P"."VALUE"='640'))
   3 - filter("CTXSYS"."CONTAINS"(:B1,'({country} INPATH
              (/class/class_type)) and ({640} INPATH (/class/values/value))')>0)
   4 - filter("P"."CLASS_TYPE"='country' AND "P"."VALUE"='640')

Note
-----
   - dynamic statistics used: dynamic sampling (level=2)

SQL>

【讨论】：