[英]MS-SQLSERVER - SQL Query using ROW_NUMBER taking long time with 0 result from query
select autoid from (SELECT ROW_NUMBER() OVER (ORDER
BY MYTABLE.DETECTEDUTC DESC) as rownum, autoId from
MYTABLE where MYTABLE.guid in (..guids..)) as tab1 where rownum >=1000 and rownum < 1020
我們有一個表MYTABLE,該表可能包含數百萬條記錄,當前它有1000萬條記錄。 上面的SQL查詢用於在我們的代碼中獲取分頁數據,在查詢給出結果之前它可以正常工作,但是如果查詢返回0個結果,則掛起數小時。 同樣,SQL Server在運行以上查詢時會開始消耗系統RAM,並且不會返回任何記錄。
另一方面,以下查詢可以很好地處理0個結果-
select autoid from (SELECT ROW_NUMBER() OVER (ORDER
BY MYTABLE.DETECTEDUTC DESC) as rownum, autoId from
MYTABLE where MYTABLE.guid in( ..guids..)) as tab1
不管查詢中的問題如何,我都會介紹我通常實現分頁的方式:
作為輸入(例如,對於存儲過程):
@fromIndex int = 0 -- default starting from index 0
@count int = 10 -- default returning 10 items per page
通用SQL邏輯:
CREATE TABLE #PaginatedItems (
Column1 int, -- declare your needed columns here
Column2 varchar(50),
rowIndex int -- needed for pagination logic
);
WITH OrderedItems AS
(
SELECT
SourceTable.Col1, -- will end up in #PaginatedItems.Column1
SourceTable.Col2,
ROWNUMBER() OVER (
ORDER BY <sort criteria>
) AS rowIndex
FROM
SourceTable
)
INSERT INTO
#PaginatedItems
SELECT
*
FROM
OrderedItems
WHERE
rowIndex >= @fromIndex + 1 AND rowIndex <= @fromIndex + @count
SELECT * FROM #PaginatedItems -- the query that returns the items
希望這可以幫助。
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