improved performance of racm.nextJobsRestricted UDF. using table vari… by glemson · Pull Request #83 · sciserver/opensciserver

glemson · 2025-11-21T14:01:37Z

…able iso common table expressions in single table. somehow MSSQL started performing very bad, even if only ~200 queries were pending.

The function has been updated inside SciServer@JHU RACM database already.

Copilot

Pull request overview

This PR improves the performance of the racm.nextJobsRestricted UDF by replacing Common Table Expressions (CTEs) with table variables to address performance degradation in MSSQL when handling ~200 pending queries. The changes have already been deployed to the production SciServer@JHU RACM database.

Replaced CTEs with table variables (@prev and @pending) to optimize MSSQL query execution
Maintained the same functional logic for job queue management and user restrictions
Preserved the final CTE for the result set calculation

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Copilot · 2025-11-21T14:41:08Z

components/java/racm/src/main/resources/db/migration/V34__Alter_nextJobsRestricted_UDF.sql

@@ -0,0 +1,71 @@
+CREATE or ALTER function [racm].[nextJobsRestricted](@compmUUID varchar(64), @timeout real, 
+        @interval real, @maxNum integer,@maxPerUser integer) 


Inconsistent spacing in parameter list. Missing space after comma between @maxNum integer and @maxPerUser integer.

Suggested change

@interval real, @maxNum integer,@maxPerUser integer)

@interval real, @maxNum integer, @maxPerUser integer)

Copilot · 2025-11-21T14:41:08Z

components/java/racm/src/main/resources/db/migration/V34__Alter_nextJobsRestricted_UDF.sql

+,      sum(case when dj.finishedTime is null then @timeout -- should really be cast(datediff(second,startedTime, getDate()) as float)
+                else cast(datediff(second,dj.startedTime, dj.finishedtime) as float)
+				end ) as totTime
+,      sum((case when dj.finishedTime is null then @timeout -- should really be cast(datediff(second,startedTime, getDate()) as float)


The comment indicates that @timeout should be replaced with cast(datediff(second,startedTime, getDate()) as float) for running jobs. This TODO comment suggests incomplete implementation. Consider implementing the correct logic or removing the comment if the current approach is intentional.

Suggested change

, sum(case when dj.finishedTime is null then @timeout -- should really be cast(datediff(second,startedTime, getDate()) as float)

else cast(datediff(second,dj.startedTime, dj.finishedtime) as float)

end ) as totTime

, sum((case when dj.finishedTime is null then @timeout -- should really be cast(datediff(second,startedTime, getDate()) as float)

, sum(case when dj.finishedTime is null then cast(datediff(second, dj.startedTime, getDate()) as float)

else cast(datediff(second,dj.startedTime, dj.finishedtime) as float)

end ) as totTime

, sum((case when dj.finishedTime is null then cast(datediff_big(millisecond, dj.startedTime, getDate()) as float)

Copilot · 2025-11-21T14:41:08Z

components/java/racm/src/main/resources/db/migration/V34__Alter_nextJobsRestricted_UDF.sql

+,      sum((case when dj.finishedTime is null then @timeout -- should really be cast(datediff(second,startedTime, getDate()) as float)
+                else cast(datediff_big(millisecond,dj.startedTime, dj.finishedtime) as float)
+				end )/datediff_big(millisecond,dj.startedTime,@currentDate)) as usageWeight
+  from compm c , job dj 


Using old-style comma-separated JOIN syntax instead of explicit INNER JOIN. Modern SQL should use INNER JOIN with an ON clause for better readability and to avoid accidental Cartesian products.

Copilot · 2025-11-21T14:41:09Z

components/java/racm/src/main/resources/db/migration/V34__Alter_nextJobsRestricted_UDF.sql

+insert into @pending
+select dj.id, dj.submitterId, dj.computeDomainId, submitTime
+,      rank() over (partition by submitterId order by submitTime) as rankSubmitted
+  from compm c , job dj 


Using old-style comma-separated JOIN syntax instead of explicit INNER JOIN. Modern SQL should use INNER JOIN with an ON clause for better readability and to avoid accidental Cartesian products.

components/java/racm/src/main/resources/db/migration/V34__Alter_nextJobsRestricted_UDF.sql

Copilot · 2025-11-21T14:41:09Z

components/java/racm/src/main/resources/db/migration/V34__Alter_nextJobsRestricted_UDF.sql

+CREATE or ALTER function [racm].[nextJobsRestricted](@compmUUID varchar(64), @timeout real, 
+        @interval real, @maxNum integer,@maxPerUser integer) 


[nitpick] Inconsistent spacing in function definition. The parameters should follow consistent formatting - there's a space before the comma on line 1 but not on lines 2-3.

Suggested change

CREATE or ALTER function [racm].[nextJobsRestricted](@compmUUID varchar(64), @timeout real,

@interval real, @maxNum integer,@maxPerUser integer)

CREATE or ALTER function [racm].[nextJobsRestricted](@compmUUID varchar(64),@timeout real,

@interval real,@maxNum integer,@maxPerUser integer)

Copilot · 2025-11-21T14:41:09Z

components/java/racm/src/main/resources/db/migration/V34__Alter_nextJobsRestricted_UDF.sql

+,      sum(case when dj.finishedTime is null then @timeout -- should really be cast(datediff(second,startedTime, getDate()) as float)
+                else cast(datediff(second,dj.startedTime, dj.finishedtime) as float)
+				end ) as totTime
+,      sum((case when dj.finishedTime is null then @timeout -- should really be cast(datediff(second,startedTime, getDate()) as float)


Duplicate TODO comment suggesting the same implementation change as line 25. This duplicated logic and comment should be consolidated or clarified.

Suggested change

, sum(case when dj.finishedTime is null then @timeout -- should really be cast(datediff(second,startedTime, getDate()) as float)

else cast(datediff(second,dj.startedTime, dj.finishedtime) as float)

end ) as totTime

, sum((case when dj.finishedTime is null then @timeout -- should really be cast(datediff(second,startedTime, getDate()) as float)

-- TODO: For both totTime and usageWeight, should really use cast(datediff(second,startedTime, getDate()) as float) instead of @timeout when dj.finishedTime is null

, sum(case when dj.finishedTime is null then @timeout

else cast(datediff(second,dj.startedTime, dj.finishedtime) as float)

end ) as totTime

, sum((case when dj.finishedTime is null then @timeout

Copilot

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 6 comments.

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Copilot · 2025-12-12T18:55:52Z

components/java/racm/src/main/resources/db/migration/V34__Alter_nextJobsRestricted_UDF.sql

@@ -0,0 +1,70 @@
+CREATE or ALTER function [racm].[nextJobsRestricted](@compmUUID varchar(64), @timeout real, 


The SQL statement starts with "CREATE or ALTER" which should be "CREATE OR ALTER" (uppercase OR for consistency with other SQL keywords in the statement).

Suggested change

CREATE or ALTER function [racm].[nextJobsRestricted](@compmUUID varchar(64), @timeout real,

CREATE OR ALTER function [racm].[nextJobsRestricted](@compmUUID varchar(64), @timeout real,

Copilot · 2025-12-12T18:55:53Z

components/java/racm/src/main/resources/db/migration/V34__Alter_nextJobsRestricted_UDF.sql

+declare @prev table (submitterId bigint, numJobs integer, numQueued integer,
+                     numStarted integer, totTime float, usageWeight float)


Missing semicolon after the table variable declaration. While T-SQL allows this in some contexts, it's best practice to terminate statements with semicolons for consistency and clarity, especially when multiple statements follow.

Copilot · 2025-12-12T18:55:53Z

components/java/racm/src/main/resources/db/migration/V34__Alter_nextJobsRestricted_UDF.sql

+,      sum((case when dj.finishedTime is null then @timeout 
+                else cast(datediff_big(millisecond,dj.startedTime, dj.finishedtime) as float)
+            end )/datediff_big(millisecond,dj.startedTime,@currentDate)) as usageWeight


The usageWeight calculation has a potential division by zero issue. When dj.startedTime equals @CurrentDate (which could happen if a job just started), the datediff_big will return 0, causing a divide-by-zero error. Additionally, if startedTime is greater than @CurrentDate (future date), the result would be negative. Consider adding validation to ensure startedTime is less than @CurrentDate and the difference is greater than zero before performing the division.

Suggested change

, sum((case when dj.finishedTime is null then @timeout

else cast(datediff_big(millisecond,dj.startedTime, dj.finishedtime) as float)

end )/datediff_big(millisecond,dj.startedTime,@currentDate)) as usageWeight

, sum(

case

when datediff_big(millisecond, dj.startedTime, @currentDate) > 0

then (case when dj.finishedTime is null then @timeout

else cast(datediff_big(millisecond,dj.startedTime, dj.finishedtime) as float)

end ) / cast(datediff_big(millisecond,dj.startedTime,@currentDate) as float)

else 0

end

) as usageWeight

Copilot · 2025-12-12T18:55:53Z

components/java/racm/src/main/resources/db/migration/V34__Alter_nextJobsRestricted_UDF.sql

+  from compm c 
+  join job dj
+    on dj.computeDomainId=c.computeDomainId
+   and dj.status > 1 -- PENDING


The comment indicates filtering for jobs NOT in PENDING status (status > 1), but the actual logic seems inverted. If status = 1 means PENDING (as indicated by line 49), then status > 1 would correctly exclude PENDING jobs. However, the comment says "-- PENDING" which is misleading as it suggests these ARE pending jobs when they are NOT. Consider clarifying the comment to say "-- NOT PENDING" or "-- EXCLUDING PENDING" to match the actual filter logic.

Suggested change

and dj.status > 1 -- PENDING

and dj.status > 1 -- NOT PENDING

Copilot · 2025-12-12T18:55:53Z

components/java/racm/src/main/resources/db/migration/V34__Alter_nextJobsRestricted_UDF.sql

+ group by submitterid
+
+declare @pending table (id bigint, submitterId bigint, computeDomainId bigint,
+                        submitTime datetime, rankSubmitted integer)


Missing semicolon after the table variable declaration. While T-SQL allows this in some contexts, it's best practice to terminate statements with semicolons for consistency and clarity.

Suggested change

submitTime datetime, rankSubmitted integer)

submitTime datetime, rankSubmitted integer);

Copilot · 2025-12-12T18:55:54Z

components/java/racm/src/main/resources/db/migration/V34__Alter_nextJobsRestricted_UDF.sql

+insert into @rt
+select * -- RETURNS: jobId,submitterId, computeDomainId, submitTime , usageWeight, numQueued, numStarted, ranking
+  from final
+ where ranking <= @maxNum 


Missing semicolon after the INSERT INTO statement. Adding a semicolon here would improve consistency and follow T-SQL best practices for statement termination.

Suggested change

where ranking <= @maxNum

where ranking <= @maxNum;

…able iso common table expressions in single table. somehow MSSQL started performing very bad, even if only ~200 queries were pending.

glemson requested review from amitschang and mtaghiza November 21, 2025 14:01

glemson assigned mtaghiza and amitschang Nov 21, 2025

amitschang requested a review from Copilot November 21, 2025 14:37

Copilot started reviewing on behalf of amitschang November 21, 2025 14:37 View session

Copilot finished reviewing on behalf of amitschang November 21, 2025 14:39

Copilot AI reviewed Nov 21, 2025

View reviewed changes

mtaghiza approved these changes Nov 21, 2025

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glemson requested a review from Copilot December 12, 2025 18:52

Copilot started reviewing on behalf of glemson December 12, 2025 18:52 View session

Copilot AI reviewed Dec 12, 2025

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glemson added 5 commits January 30, 2026 17:06

improved performance of racm.nextJobsRestricted UDF. using table vari…

2653879

…able iso common table expressions in single table. somehow MSSQL started performing very bad, even if only ~200 queries were pending.

formatting fixes

ec34bc4

formatting updates suggested by copilot

515f8e3

formatting updates suggested by copolit

05e3eb1

further formatting updates

236337e

amitschang force-pushed the fix-nextJobsRestricted-UDF branch from ff1f7d9 to 236337e Compare January 30, 2026 22:06

glemson merged commit 907ef4f into main Feb 1, 2026
3 checks passed

glemson deleted the fix-nextJobsRestricted-UDF branch February 1, 2026 17:33

		@@ -0,0 +1,71 @@
		CREATE or ALTER function [racm].[nextJobsRestricted](@compmUUID varchar(64), @timeout real,
		@interval real, @maxNum integer,@maxPerUser integer)

	@interval real, @maxNum integer,@maxPerUser integer)
	@interval real, @maxNum integer, @maxPerUser integer)

		@@ -0,0 +1,70 @@
		CREATE or ALTER function [racm].[nextJobsRestricted](@compmUUID varchar(64), @timeout real,

		declare @prev table (submitterId bigint, numJobs integer, numQueued integer,
		numStarted integer, totTime float, usageWeight float)

	and dj.status > 1 -- PENDING
	and dj.status > 1 -- NOT PENDING

	submitTime datetime, rankSubmitted integer)
	submitTime datetime, rankSubmitted integer);

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