Has my Azure Synapse dedicated SQL Pool locked itself up?

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iw-0618 asked Apr 22, '22 AnnuKumari-MSFT commented May 4, '22

Has my Azure Synapse dedicated SQL Pool locked itself up?

I have a query in a synapse dedicated sql pool that has been suspended for over an hour. From what I know, a suspended query indicates that the query is waiting for a concurrency spot.
I have a process that was inserting data into a replicated table (lets say its called MyTable). The very next query was to select all records from MyTable but that query is now suspended.
If have run the following query:

 SELECT    *
 FROM    sys.dm_pdw_resource_waits

which produces:

Why would I still be having queued requests when there are no concurrency spots being used?

azure-synapse-analytics

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AnnuKumari-MSFT · Apr 26 at 04:24 AM

Hi @iw-0618 ,
Thankyou for using Microsoft Q&A platform and thanks for raising your question here.

As I understand your issue , you are running query in dedicated SQL pool , however, it is getting suspended even when there is no concurrency slots getting used. Please let me know if my understanding about your query is incorrect.

I can see there is no resource class assigned to these queries.

To ensure each query has enough resources to execute efficiently, Synapse SQL tracks resource utilization by assigning concurrency slots to each query. The system puts queries into a queue based on importance and concurrency slots. Queries wait in the queue until enough concurrency slots are available.

With the introduction of workload groups, the concept of concurrency slots no longer applies. Resources per request are allocated on a percentage basis and specified in the workload group definition. However, even with the removal of concurrency slots, there are minimum amounts of resources needed per queries based on the service level.

Please view this article to know more about Concurrency maximums for workload groups

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AnnuKumari-MSFT AnnuKumari-MSFT · May 04 at 08:32 AM

Hi @iw-0618 ,
We haven’t heard from you on the last response and was just checking back to see if the query has been answered.

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