Yii2模式扫描ALL_OBJECTS而不是USER_OBJECTS？

Posted 2021-05-04

为什么Yii2使用ALL_OBJECTS扫描架构，然后按OWNER =“owner_name”进行过滤，而不是仅扫描USER_OBJECTS？

出于某种原因，扫描ALL_OBJECTS时查询需要很长的执行时间（45秒），查询USER_OBJECTS时需要大约2秒钟。 （生产环境）

SELECT
    A.COLUMN_NAME,
    A.DATA_TYPE,
    A.DATA_PRECISION,
    A.DATA_SCALE,
    A.DATA_LENGTH,
    A.NULLABLE,
    A.DATA_DEFAULT,
    COM.COMMENTS AS COLUMN_COMMENT
FROM ALL_TAB_COLUMNS A
    INNER JOIN ALL_OBJECTS B ON B.OWNER = A.OWNER AND LTRIM(B.OBJECT_NAME) = LTRIM(A.TABLE_NAME)
    LEFT JOIN ALL_COL_COMMENTS COM ON (A.OWNER = COM.OWNER AND A.TABLE_NAME = COM.TABLE_NAME AND A.COLUMN_NAME = COM.COLUMN_NAME)
WHERE
    A.OWNER = 'owner_name'
    AND B.OBJECT_TYPE IN ('TABLE', 'VIEW', 'MATERIALIZED VIEW')
    AND B.OBJECT_NAME = 'object_name'
ORDER BY A.COLUMN_ID

谢谢

答案

访问ALL_*views / synonyms和USER_* views / synonym之间的区别。

ALL_OBJECTS描述了当前使用可访问的所有对象，而USER_OBJECTS仅列出属于当前用户的对象。