2
我有性能问题与此特定的查询:的Oracle 11g:查询性能优化
SELECT ID,
NAME,
CREATION_DATE,
MODIFICATION_DATE,
CREATION_USER,
MODIFICATION_USER,
CODE,
START_DATE,
TO_CHAR(ANSWER) AS ANSWER,
STATUS,
RESUME,
REQUIRED,
RTRIM(
XMLAGG(
XMLELEMENT(E,QW.WARD_ID,',').EXTRACT('//text()')
ORDER BY QW.WARD_ID
).GetClobVal(),
','
) AS wards
FROM RD_QUESTIONS Q
LEFT JOIN RD_QUESTIONS_WARDS QW ON QW.QUESTION_ID = ID
GROUP BY ID,
NAME,
CREATION_DATE,
MODIFICATION_DATE,
CREATION_USER,
MODIFICATION_USER,
CODE,
START_DATE,
TO_CHAR(ANSWER),
STATUS,
RESUME,
REQUIRED
DDL
CREATE TABLE RD_QUESTIONS(
ID NUMBER(38, 0),
NAME VARCHAR(255) NOT NULL,
CREATION_DATE TIMESTAMP(6),
MODIFICATION_DATE TIMESTAMP(6),
CREATION_USER VARCHAR(20),
MODIFICATION_USER VARCHAR(20),
SECTION_ID NUMBER(38, 0),
CHAPTER_ID NUMBER(38, 0),
CONSTRAINT RD_QUESTIONS_PK3 PRIMARY KEY (ID),
);
CREATE TABLE RD_QUESTIONS_WARDS(
QUESTION_ID NUMBER(38, 0),
WARD_ID NUMBER(38, 0),
CONSTRAINT RD_QUESTIONS_WARDS_PK4 PRIMARY KEY (QUESTION_ID, WARD_ID),
CONSTRAINT RD_QUESTIONS_FK4 FOREIGN KEY (QUESTION_ID) REFERENCES RD_QUESTIONS(ID)
);
问题的发言RTRIM(XMLAGG(XMLELEMENT(E,WARD_ID,',').EXTRACT('//text()') ORDER BY WARD_ID).GetClobVal(),',') AS wards
那就是计算很慢。
我在找的结果是一个名为“病房”的列,所有匹配的ID都加入到一个字符串中。
任何人都有更好的性能解决方案?
请你能给的DDL两个表,并编辑查询,以显示该表中的各列属于因为这将让你选择一个巨大的差异。即它是'Q.WARD_ID'还是'QW.WARD_ID'(对于其他列也是类似的) – MT0