Dynamic SQL running way too longer - sql

Question

I am trying to run a dynamic SQL query that is supposed to load more than 200M records. I tried to load all the records at once but got 'System.OutOfMemory' Exception hence decided to break the time-interval into months.The following runs for more than an hour even though if I run it for just a month. I hard-coded the dates and ran it without the 'While' and it runs normally. Can someone check and let me know if there is some error in it.
Below is my query
DECLARE #FromDate VARCHAR(MAX)='',
#params nvarchar(max) = N'#StartDate Date out,#EndDate Date out,#FromDate date out,#ToDate date out',
#SQL NVARCHAR(MAX)=’’,
#ToDate VARCHAR(MAX)='',
#StartDate VARCHAR(MAX)=’’,
#EndDate VARCHAR(MAX)=’’;
SELECT #FromDate= DATEADD(DAY,-365, GETUTCDATE()), #ToDate = GETUTCDATE();
SELECT #StartDate=#FromDate, #EndDate=CAST(DATEADD(MONTH,1, #FromDate) AS DATE);
SET #SQL = '
WHILE ''' + #FromDate + ''' < ''' + #ToDate + '''
BEGIN
INSERT INTO dbo.Sales
(
ProductID,
SaleDate,
Quantity
)
Select
ProductID,
SaleDate,
Quantity
from
OPENQUERY(TeraData1,''
Select
PR_ID AS ProductID,
SL_Date AS SaleDate,
PR_QTY AS Quantity
FROM
Sales.Product
where
SaleDate BETWEEN ' + #StartDate + 'AND '+ #EndDate + '
'')
SET #FromDate =DATEADD(MONTH,1,'''+ #FromDate +''')
SET #StartDate =DATEADD(MONTH,1,'''+ #StartDate +''')
SET #EndDate =DATEADD(MONTH,1,'''+ #EndDate +''')
END’
EXECUTE sp_executesql #SQL, #params,
#FromDate=#FromDate,
#ToDate=#ToDate,
#StartDate = #StartDate out,
#EndDate = #EndDate out;

Answer 1

DECLARE #FromDate DATE
SET #FromDate = DATEADD(YEAR,-1,GETUTCDATE())
WHILE #FromDate < GETUTCDATE()
BEGIN
INSERT INTO dbo.Sales
(
ProductID,
SaleDate,
Quantity
)
Select
ProductID,
SaleDate,
Quantity
from
OPENQUERY(TeraData1,
Select
PR_ID AS ProductID,
SL_Date AS SaleDate,
PR_QTY AS Quantity
FROM
Sales.Product
where
SaleDate >= #FromDate AND SaleDate < DATEADD(MONTH,1,#FromDate)
)
SET #FromDate =DATEADD(MONTH,1,#FromDate)
END
It looks like you have way more variables/dates than you need and that you don't need dynamic SQL unless you are wanting to pass the linked server name or some other column dynamically.
Also stick with the appropriate datatype for the parameter instead of letting SQL infer the values you want.
Also your use of BETWEEN for the dates would have duplicated the certain dates because it would be inclusive, to fix limit 1 side of the comparison.
If you do want to do this dynamically keep the control flow in your non dynamic SQL and pass the parameter here is an example:
DECLARE #FromDate DATE
SET #FromDate = DATEADD(YEAR,-1,GETUTCDATE())
WHILE #FromDate < GETUTCDATE()
BEGIN
DECLARE #LinkedServerName NVARCHAR(MAX) = 'TeraData1'
DECLARE #ParamDef NVARCHAR(MAX) = '#FromDate DATE'
DECLARE #SQL NVARCHAR(MAX)
SET #SQL = '
INSERT INTO dbo.Sales
(
ProductID,
SaleDate,
Quantity
)
Select
ProductID,
SaleDate,
Quantity
from
OPENQUERY(' + #LinkedServerName + ',
Select
PR_ID AS ProductID,
SL_Date AS SaleDate,
PR_QTY AS Quantity
FROM
Sales.Product
where
SaleDate >= #FromDate AND SaleDate < DATEADD(MONTH,1,#FromDate)
)'
EXECUTE sp_executesql #SQL, #PramDef, #FromDate = #FromDate
SET #FromDate =DATEADD(MONTH,1,#FromDate)
END