Azure Synapsis database issue

Question

I am having issue with my dataware house hosted in Azure Synapsis.

The data pipelines got failed maxing out the resources, we are having 100 DTUs at that time.

We thought that it was a resource constrains and we doubled the DTUs to 200.

the pipeline is still failing and upon checking there is not a single connection on DB and resources are still maxing out.

We have stop the DB and start it again after 40 minutes in hope the the underlying infra got changed and the problem will resolve but no change in errors afterwards. We do not make any changes in the database or the pipeline.

Here are the critical Azure activity log entries for the reference.
7f54e55a-85df-4ce0-a039-6b6d44e7ae5f

0289d2b0-309b-4bd1-8b7b-7234840b05dd

a30a81d0-3158-4c05-a2b6-fce547de5e2a

This is burning our money and we are not getting anything out of it, please help ASAP.

Answer 1

Hi @DXFactor SysOps Since you're using Azure Synapse Dedicated SQL Pools, the equivalent term is DWUs (like DW100c, DW200c, etc.). Assuming you meant DWUs and already scaled up, that was definitely a good first step but sounds like something deeper is going on.

Here are a few things recommend checking:

Are any queries actually running or stuck: Sometimes it looks like there are no active connections, but background queries can still be holding up resources. Run this

SELECT * FROM sys.dm_pdw_exec_requests 
WHERE status NOT IN ('Completed', 'Failed', 'Cancelled');

This shows if anything is stuck in a running or queued state.

Any chance it’s a distribution skew issue: If one of your tables is unevenly distributed, it can overload specific nodes even with extra DWUs. Here’s a quick check:

SELECT distribution_id, COUNT(*) 
FROM sys.pdw_nodes_tables 
WHERE object_id = OBJECT_ID('<your_table_name>')
GROUP BY distribution_id;

If one or two distributions have way more rows than the others, it’s worth revisiting your distribution key or switching to round-robin as a quick fix.

When was the last time stats were updated: Outdated statistics or missing indexes can silently wreck performance. Try:

EXEC sp_updatestats;

Also check if your large tables are using clustered columnstore indexes that’s the most efficient format in Synapse for big data sets.

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I hope this information helps. Please do let us know if you have any further queries.

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