How to avoid this T-SQL statement affecting my TempDB?

Question

How to avoid this T-SQL statement affecting my TempDB?

Charmer

SSChampion

Points: 14903
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August 28, 2012 at 7:22 am

#393036

WITH CTE AS (SELECT DISTINCT
LTRIM(RTRIM(P.IncidentIDRef)) AS MODIDREF, P.JurisID, P.EntDttm AS CREATEDDTTM, P.DIDCU AS CREATEDPFIDREF, 'INC' AS MODCODE, 'C' RECTYPE,
REPLACE(STUFF
((SELECT '' + C.FDNARR
FROM PSFDOC C
WHERE C.FDDOC# = T .FDDOC#
ORDER BY C.FDDOC#, C.FDLINE FOR XML PATH('')), 1, 10, ''), '', '') AS COMMENT
FROM PSFDOC T JOIN
PSDOCI P ON P.DIDOC# = T .FDDOC#
WHERE P.DIFILE = 'PLINCD' AND (NOT P.DIDESC IN ('cad system narrative', 'dispatch narrative')) AND P.DIDESC NOT LIKE 'Converted Cad Comment%')
SELECT *, CAST(CTE .COMMENT AS NVARCHAR(MAX)) AS COMMENT1, ROW_NUMBER() OVER (PARTITION BY CTE .JURISID, CTE .MODIDREF
ORDER BY CTE .JURISID, CTE .MODIDREF) - 1 AS SEQNO
FROM CTE
This SQL statement is affecting my Temp Db around 11 GB....Help me friends ...I need alternate SQL statement not to affect my temp db..
I have attached the estimated execution plan of this statement...If you need anything let me know please.
Give me suggestions please..
Thanks,
Charmer

Viewing 11 posts - 1 through 10 (of 10 total)

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GSquared SSC Guru Points: 260824 More actions · Answer 1

The only way I see to possibly avoid tempdb on this one would be to build permanent tables, do the work in them that tempdb is doing in worktables, and use those instead of the CTE. But even that isn't likely to work, because the SQL engine will still need to do sorts on the data, for the distinct and row number operations at the very least, and that's usually done in tempdb.

If it's blowing tempdb up by 11 Gig, I'm assuming this query is dealing with a huge amount of data. Can you filter the data before-hand, in a separate table or query? That will still use tempdb, probably, but might use less of it.

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Charmer SSChampion Points: 14903 More actions · Answer 2

GSquared (8/28/2012)
The only way I see to possibly avoid tempdb on this one would be to build permanent tables, do the work in them that tempdb is doing in worktables, and use those instead of the CTE. But even that isn't likely to work, because the SQL engine will still need to do sorts on the data, for the distinct and row number operations at the very least, and that's usually done in tempdb.
If it's blowing tempdb up by 11 Gig, I'm assuming this query is dealing with a huge amount of data. Can you filter the data before-hand, in a separate table or query? That will still use tempdb, probably, but might use less of it.

Yes you are absolutely correct. This table has records around 6 million...

ok GSquared, as you say let me filter the records in separate table and will work on it and i will let you know how things going on..

Thanks,
Charmer

Suresh B. SSC-Insane Points: 22986 More actions · Answer 3

Is "ORDER BY C.FDDOC#, C.FDLINE" required?

What is the type of C.FDLINE?

Creating an index on C.FDDOC#, C.FDLINE should imporve the tempdb size and execution time.

Charmer SSChampion Points: 14903 More actions · Answer 4

Suresh B. (8/29/2012)
Is "ORDER BY C.FDDOC#, C.FDLINE" required?
What is the type of C.FDLINE?
Creating an index on C.FDDOC#, C.FDLINE should imporve the tempdb size and execution time.

Yes, order is must because concatenation is based on this order columns.

I have created a staging table and filtered the records as GSquared said.

Now, the performance is so good. but it still affects the temp db. But anyway i am happy:-) with the results since temp db is affected only about 700 MB where it was affected around 11 GB earlier.

Thanks,
Charmer

GSquared SSC Guru Points: 260824 More actions · Answer 5

Glad we could help.

- Gus "GSquared", RSVP, OODA, MAP, NMVP, FAQ, SAT, SQL, DNA, RNA, UOI, IOU, AM, PM, AD, BC, BCE, USA, UN, CF, ROFL, LOL, ETC
Property of The Thread

"Nobody knows the age of the human race, but everyone agrees it's old enough to know better." - Anon

Charmer SSChampion Points: 14903 More actions · Answer 6

GSquared (8/29/2012)
Glad we could help.

Thank you so much, Pal...I really appreciate your suggestions

Thanks,
Charmer

ChrisM@Work SSC Guru Points: 186127 More actions · Answer 7

Try putting the FOR XML PATH stringinator into a CROSS APPLY, where it can crunch up the rows of PSFDOC separately from the rest of the query. You might not even need the DISTINCT:

;WITH CTE AS (

SELECT --DISTINCT

LTRIM(RTRIM(P.IncidentIDRef)) AS MODIDREF,

P.JurisID,

P.EntDttm AS CREATEDDTTM,

P.DIDCU AS CREATEDPFIDREF,

'INC' AS MODCODE,

'C' RECTYPE,

x.Comment

FROM PSDOCI P

CROSS APPLY (

SELECT COMMENT = REPLACE(STUFF(

(SELECT '' + C.FDNARR

FROM PSFDOC C

WHERE C.FDDOC# = P.DIDOC#

ORDER BY C.FDDOC#, C.FDLINE FOR XML PATH(''))

, 1, 10, ''), '', '')

) x

--JOIN PSFDOC T

--ON P.DIDOC# = T .FDDOC#

WHERE P.DIFILE = 'PLINCD'

AND (NOT P.DIDESC IN ('cad system narrative', 'dispatch narrative'))

AND P.DIDESC NOT LIKE 'Converted Cad Comment%'

)

SELECT

*,

CAST(CTE.COMMENT AS NVARCHAR(MAX)) AS COMMENT1,

ROW_NUMBER() OVER (PARTITION BY CTE .JURISID, CTE .MODIDREF ORDER BY CTE .JURISID, CTE .MODIDREF) - 1 AS SEQNO

FROM CTE

^{“Write the query the simplest way. If through testing it becomes clear that the performance is inadequate, consider alternative query forms.” - Gail Shaw}

For fast, accurate and documented assistance in answering your questions, please read this article.
Understanding and using APPLY, (I) and (II) Paul White
Hidden RBAR: Triangular Joins / The "Numbers" or "Tally" Table: What it is and how it replaces a loop Jeff Moden

Charmer SSChampion Points: 14903 More actions · Answer 8

ChrisM@Work (8/29/2012)
Try putting the FOR XML PATH stringinator into a CROSS APPLY, where it can crunch up the rows of PSFDOC separately from the rest of the query. You might not even need the DISTINCT:
;WITH CTE AS (
SELECT --DISTINCT
LTRIM(RTRIM(P.IncidentIDRef)) AS MODIDREF,
P.JurisID,
P.EntDttm AS CREATEDDTTM,
P.DIDCU AS CREATEDPFIDREF,
'INC' AS MODCODE,
'C' RECTYPE,
x.Comment
FROM PSDOCI P
CROSS APPLY (
SELECT COMMENT = REPLACE(STUFF(
(SELECT '' + C.FDNARR
FROM PSFDOC C
WHERE C.FDDOC# = P.DIDOC#
ORDER BY C.FDDOC#, C.FDLINE FOR XML PATH(''))
, 1, 10, ''), '', '')
) x
--JOIN PSFDOC T
--ON P.DIDOC# = T .FDDOC#
WHERE P.DIFILE = 'PLINCD'
AND (NOT P.DIDESC IN ('cad system narrative', 'dispatch narrative'))
AND P.DIDESC NOT LIKE 'Converted Cad Comment%'
)
SELECT
*,
CAST(CTE.COMMENT AS NVARCHAR(MAX)) AS COMMENT1,
ROW_NUMBER() OVER (PARTITION BY CTE .JURISID, CTE .MODIDREF ORDER BY CTE .JURISID, CTE .MODIDREF) - 1 AS SEQNO
FROM CTE

This one also works really great...Thank you Chris

Thanks,
Charmer

ChrisM@Work SSC Guru Points: 186127 More actions · Answer 9

Thanks for the feedback. The original table had an unnecessary join which the new query eliminates, and if you can remove the DISTINCT now, then you remove a memory-hogging SORT too.

^{“Write the query the simplest way. If through testing it becomes clear that the performance is inadequate, consider alternative query forms.” - Gail Shaw}

For fast, accurate and documented assistance in answering your questions, please read this article.
Understanding and using APPLY, (I) and (II) Paul White
Hidden RBAR: Triangular Joins / The "Numbers" or "Tally" Table: What it is and how it replaces a loop Jeff Moden

Charmer SSChampion Points: 14903 More actions · Answer 10

ChrisM@Work (8/30/2012)
Thanks for the feedback. The original table had an unnecessary join which the new query eliminates, and if you can remove the DISTINCT now, then you remove a memory-hogging SORT too.

yes..i really felt that in the performance...

Thanks,
Charmer