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Category: Error Handling

Transaction Isolation Level Changes in Azure SQL MI

Published 2023-10-31 by Kevin Feasel

Emre Gokoglu goes through a customer issue:

In this technical article, we will delve into an interesting case where a customer encountered problems related to isolation levels in Azure SQL Managed Instance. Isolation levels play a crucial role in managing the concurrency of database transactions and ensuring data consistency. We will start by explaining isolation levels and providing examples of their usage. Then, we will summarize and describe the customer’s problem in detail. Finally, we will go through the analysis of the issue.

This post describes an interesting difference between on-premises SQL Server and Azure SQL Managed Instance in terms of how they handle wrapping multiple connections in a single transaction scope. It’s also the type of thing I would not have thought of when testing a cloud solution like Azure SQL MI or Azure SQL DB versus on-premises SQL Server.

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Automating SQL Dump Analysis

Published 2023-10-27 by Kevin Feasel

Sean Gallardy has been busy:

One of the things that is lacking in the community is for some simple dump analysis for SQL Server, well no longer!

Introducing the Beta version of SQL Dump Analysis… sure it’s not super pretty, sure it’s not 100% yet… but it’ll give you the basic goods and get you on your way.

This is a website you upload SQL dumps to, rather than an executable you’d download. Still, check it out.

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SSIS Catalog Error 27150

Published 2023-10-27 by Kevin Feasel

Andy Leonard diagnoses an error:

In case you’ve never encountered SSIS Catalog Error 27150, the error message reads:

The version of the project has changed since the instance of the execution has been created. Create a new execution instance and try again.

A customer recently encountered this error.
So… what happened?

Click through for the answer. I’ve had this happen as well for the same reason as Andy.

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Debugging SQLPackage Issues in Powershell

Published 2023-10-23 by Kevin Feasel

Jose Manuel Jurado Diaz simplifies SQLPackage output:

Handling massive SQLPackage diagnostic logs, like those spanning over 4 million rows, can be an overwhelming task when troubleshooting support cases. This article introduces a PowerShell script designed to efficiently parse through SQLPackage diagnostic logs, extract error messages, and save them to a separate file, thus simplifying the review process and enhancing the debugging experience.

Click through for a Powershell script that can help.

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Oracle Errors: Snapshot Too Old and LOB Columns

Published 2023-10-12 by Kevin Feasel

David Fitzjarrell tackles a pair of errors:

One of the few errors taht strikes fear in the heart of a DBA is the dreaded:

ORA-01555 snapshot too old
and
ORA-22924 snapshot too old

Of course there are plenty of blogs instructing the DBA to simply “increase the undo_retention”, and there are cases where this works as expected. However, LOBs can be different as two different mechanisms exist for undo management. A LOB column can be configured to use retention to manage before mages of the data, but that can be confusing as each LOB column MAY have its own retention setting. The DBA_LOBS view reports whether LOG column uses retention or pctversion to manage undo, and the associated setting being used. Let’s -dig into this a bit deeper.

Read on to learn more about how LOB retention works, the types of issues you can run into with it, and how to correct those issues.

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SortByColumn Set to Invalid Column ID in SSAS Tabular

Published 2023-10-09 by Kevin Feasel

Olivier Van Steenlandt troubleshoots an error:

After making these changes, we pushed our changes into Azure DevOps and our deployment pipeline started to deploy the changes to the requested environment.

While the deployment process was executing, it stopped and failed promptly. We ran into an issue: “SortByColumn property set to an invalid column ID”

Read on to see the ultimate cause of and solution to the problem.

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In-Memory OLTP and Memory Allocation

Published 2023-10-09 by Kevin Feasel

Tanayankar Chakraborty explains an error:

We recently encountered a support case where a customer using In-memory tables in an Azure SQL DB, receives an error message while trying to insert data into the table that also has a clustered columnstore index. The customer then deleted the entire data from the In-memory Tables (With the clustered columnstore index), however it appeared that the Index Unused memory was still not released. Here’s the memory allocation the customer could see:

Error

In addition to the error above- here is the error text:

Msg 41823, Level 16, State 109, Line 1

Could not perform the operation because the database has reached its quota for in-memory tables. This error may be transient. Please retry the operation. See ‘http://go.microsoft.com/fwlink/?LinkID=623028‘ for more information

In this case, the error ends up being a “didn’t read the manual” type of error.

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RCSI and ID-Driven ETL

Published 2023-10-06 by Kevin Feasel

Michael J. Swart shares a warning:

Yesterday, Kendra Little talked a bit about Lost Updates under RCSI. It’s a minor issue that can pop up after turning on RCSI as the default behavior for the Read Committed isolation level. But she doesn’t want to dissuade you from considering the option and I agree with that advice.

In fact, even though we turned RCSI on years ago, by a bizarre coincidence, we only came across our first RCSI-related issue very recently. But it wasn’t update related. Instead, it has to do with an ETL process. To explain it better, consider this demo:

Michael has one example solution. I could also see a “windback” run, where, instead of starting at the very end of the line for ETL, you start a few hundred rows earlier. That way, you can pick up any stragglers. It would add some overhead to the ETL task, but given that ETL jobs should be idempotent, it shouldn’t affect the end results.

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Data Center Staffing Disasters

Published 2023-10-03 by Kevin Feasel

Steve Jones reads an after-action report:

There was a failure recently at an Azure data center in Australia when a utility power sag caused equipment to trip offline at one of the Azure data centers in Australia. You can read about it here, but essentially the headline is that there were only three people on site when the incident occurred, and that caused them to be unable to restart the equipment in time before an outage occurred.

Read on to learn more about why this failed and what Steve has seen in the wild.

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