更快的SQL数据库查询

Question

I have a oracle database with over 2 million rows and 200 columns. I'm trying to query data in five columns where one of the columns is equal to the most recent date. This query below works but seems to be taking long (over 2 min) to process. Is there a different logic I can use to speed up the query?

SELECT a,b,c,date,e FROM table a WHERE a.date = (SELECT MAX(date) FROM table)

Answer 1

try rownum

SELECT * FROM (
SELECT A,B,C,DATE,E FROM TABLE A WHERE A.DATE   DESC
)
WHERE ROWNUM=1

Answer 2

you can also use another similar solution

with  tbl1 as 
(SELECT A,B,C,DATE,E,
       first_value(date) over( order by date desc) maxdate
   FROM TABLE A)
select A,B,C,DATE,E from tbl1 where date = maxdate

Answer 3

YES !!!

Set Index "date" to your table as I_TABLE_DATE, after that change your query to this

SELECT --+ index_desc(a I_TABLE_DATE)
    a,b,c,date,e 
FROM table a 
WHERE a.date = (SELECT --+ index_desc(b I_TABLE_DATE)
                b.Date
                FROM table b
                where Rownum = 1)

it will be more faster because, during getting maximum date there will be only scanning index by descening, and your main query will work by index ascening and you dont need scan all table