Oracle使用主键列表对大型表进行分页

Question

I'm using Oracle 11.2 and am trying to write a paging query on a table with millions of rows in it. Reading other articles I think I've found the best approach but it slows down the higher the page number is.

This is my solution. First I get a list of primary key values (ID) for that page of data. I then get all the other table data matching those ids. However this still runs slowly.

SELECT *
FROM mytable
WHERE ID IN (
    SELECT ID
    FROM (
        SELECT ID, ROWNUM rnum
        FROM (
            SELECT ID
            FROM mytable
            ORDER BY ID
        ) results
        WHERE ROWNUM <= 1000010
    )
    WHERE rnum >= 1000001
 )

Execution Time: 30+ seconds.

If I do the inner query separately and manually pass the ids to the outer query it's much faster:

SELECT ID
FROM (
    SELECT ID, ROWNUM rnum
    FROM (
        SELECT ID
        FROM mytable
        ORDER BY ID
    ) results
    WHERE ROWNUM <= 1000010
)
WHERE rnum >= 1000001

Execution Time: 0.2 seconds.

Results: 
2134696,
2134697,
2134692,
2134693,
2134694,
2134695,
2134698,
2134699,
2134700,
2134701

SELECT *
FROM mytable
WHERE ID IN (
    2134696,
    2134697,
    2134692,
    2134693,
    2134694,
    2134695,
    2134698,
    2134699,
    2134700,
    2134701
)

Execution Time: 0.03 seconds.

The first query should be as fast as the other 2 together but it's much slower.

Can anyone explain why this is and suggest a better solution?

Answer 1

You first query is doing two table (or index) scans (of millions of rows) and joining them together to filter the rows.

Your second and third queries are doing a single table (or index) scan each but they are not joining them together.

You should use something like:

SELECT *
FROM (
    SELECT r.*, ROWNUM rnum
    FROM (
        SELECT *
        FROM   mytable
        ORDER BY ID
    ) r
    WHERE ROWNUM <= 1000010
)
WHERE rnum >= 1000001

Which only does a single table scan.

In Oracle 12c you can use:

SELECT   *
FROM     MYTABLE
ORDER BY id 
OFFSET 1000000 ROWS FETCH NEXT 10 ROWS ONLY

Answer 2

Best way for get total records count and records.

change [YOURTABLENAME] change 2 and 100 ( 2 "PAGENO", 100 "PERPAGE" )

with 
XPARAMS as (select 2 "PAGENO", 100 "PERPAGE" from dual)
,P2 as (select  (XPARAMS.PAGENO-1)*XPARAMS.PERPAGE "STARTNO",   XPARAMS.PAGENO*XPARAMS.PERPAGE "ENDNO" from XPARAMS)
,D1 as (select  * from [YOURTABLENAME] t order by ID)
,DCOUNT as (select count(*) "TOTALCOUNT" from D1)
,D2 as (select  rownum "RN" , D1.* from D1 )
,D3 as (select D2.* from D2,P2 where D2.RN between P2.STARTNO and p2.ENDNO )
select D3.RN, DCOUNT.TOTALCOUNT, XPARAMS.PAGENO, XPARAMS.PERPAGE, D3.* from D3,DCOUNT, XPARAMS