问Oracle 11g :元数据查询非常慢

EN

  CREATE OR REPLACE FORCE VIEW "MYDB"."COMMENTS_VIEW" ("TABLE_NAME", "COLUMN_NAME", "COMMENTS", "CONSTRAINT_TYPE", "CHECK_CONDITION") AS 
  SELECT r.TABLE_NAME, r.COLUMN_NAME, r.COMMENTS, DECODE(q.CONSTRAINT_TYPE,'P', 'Primary Key', 'C', 'Check Constraint', 'R', 'Referential Integrity Constraint' ), q.SEARCH_CONDITION AS CHECK_CONDITION
      FROM  ALL_COL_COMMENTS r -- ALL_COL_COMMENTS has the COMMENTS
          LEFT JOIN ALL_CONS_COLUMNS p ON (p.TABLE_NAME = r.TABLE_NAME AND p.OWNER = 'MYDB' AND p.COLUMN_NAME = r.COLUMN_NAME) -- ALL_CONS_COLUMNS links COLUMNS to CONSTRAINTS
          LEFT JOIN ALL_CONSTRAINTS q ON (q.OWNER = 'MYDB' AND q.CONSTRAINT_NAME = p.CONSTRAINT_NAME AND q.TABLE_NAME = p.TABLE_NAME AND (q.CONSTRAINT_TYPE = 'C' OR q.CONSTRAINT_TYPE = 'P' OR q.CONSTRAINT_TYPE = 'R' ) ) -- this gives us INFO on CONSTRAINTS
    WHERE r.OWNER = 'MYDB' 
        AND 
    r.TABLE_NAME IN ('TABLE1', 'TABLE2', 'TABLE3', 'TABLE4', 'TABLE5', 'TABLE6', 'TABLE7')
        AND
    r.COLUMN_NAME NOT IN ('CREATED', 'MODIFIED', 'CREATED_BY', 'MODIFIED_BY') 
      ORDER BY r.TABLE_NAME, r.COLUMN_NAME, r.COMMENTS;