Process data only randomly fails

Question

Hi,

I have an environment running SSAS 2019 (Tabular onprem) .

We are using the Tabular Object Model (TOM) library executing processing commands (multiple times per day).
This is done by first executing a Process data only (only on some partitions of tables) followed by a process calculate.

This usually works fine, but sometimes (maybe ones per 30 attempt) it fails with the following exception:

Microsoft.AnalysisServices.Tabular.TomInternalException: An internal error has occured.
at Microsoft.AnalysisServices.Tabular.Model.MergeAffectedSubtree(MetadataObject affectedSubtreeRoot, CopyContext mergeCopyContext)
at Microsoft.AnalysisServices.Tabular.Model.HandleImpactAffectedObjects(ServerImpact impact)
at Microsoft.AnalysisServices.Tabular.Model.ApplyImpact(ServerImpact impact)
at Microsoft.AnalysisServices.Tabular.ExecuteUtil.TryExecuteXmla(Model model, String xmlaRequest, XmlaResultCollection& xmlaResults)
at Microsoft.AnalysisServices.Tabular.Model.SaveChangesImpl(SaveOptions options)

Nothing is written in the msmdsrv.log file.

I have xevents running, catching ProgressReportEnd events (to be able to monitor performance).
Here I can see that it logs EventSubClass 58 (Sequence point Finished sequence point algorithm) just before ending, but that is also logged when the command finish with success.

It think that this is at the end of the process data only. I know that it has not started with Process calculate.

Any suggestions on what can be wrong or how to monitor it even further to find the cause?

Best Regards
Stefan

Answer 1

If it is randomly failing, I would suggest you to use sql server profile to trace the SSAS server, see which query or what event causes this crashing.