How to send Application Insights logs to a custom table with Auxiliary pricing tier in Log Analytics

Question

How to send Application Insights logs to a custom table with Auxiliary pricing tier in Log Analytics

mrcode 71

Hi,

In Azure Log Analytics Workspace there are three pricing tiers:

Analytics
Basic
Auxiliary

In the Azure portal, it’s only possible to choose between Analytics and Basic. From what I’ve read, to use the Auxiliary pricing tier, I need to create a custom table manually. (http://v4.hkg1.meaqua.org/en-us/azure/azure-monitor/logs/create-custom-table-auxiliary)

Right now, I’m using Application Insights to send logs to Azure. These logs end up in the built-in AppTraces table.

But now I want these logs to go to a custom table that uses the Auxiliary pricing tier, instead of AppTraces.

My questions:

I’ve read the documentation on how to create a custom table with the Auxiliary pricing tier - but how do I send my Application Insights logs to this custom table instead of AppTraces?
Is it possible to change the pricing tier of the AppTraces table to Auxiliary? Or do I need to create a new table with the same structure?

Any advice or documentation links would be appreciated!

Thanks in advance.

Siva shunmugam Nadessin 3,425 Reputation points Microsoft External Staff Moderator

2025-08-07T00:15:05.6+00:00
Hello mrcode,

For your question below are the answers

1.I’ve read the documentation on how to create a custom table with the Auxiliary pricing tier - but how do I send my Application Insights logs to this custom table instead of AppTraces?

Since Application Insights typically sends logs to the built- in AppTraces table, you will need to use the Logs Ingestion API to send your logs directly to the custom table you have created with the Auxiliary plan. This involves:

Creating a custom table with the Auxiliary plan.

Setting up a data collection rule and using the Logs Ingestion API to send your logs to the custom table. The custom table must have the right schema set up before you can ingest data into it. You can find detailed steps regarding the ingestion API, refer the documentation.

2. Is it possible to change the pricing tier of the AppTraces table to Auxiliary? Or do I need to create a new table with the same structure?

Unfortunately, you cannot change the pricing tier of the AppTraces table to Auxiliary. The Auxiliary plan is only supported on custom tables created via the API, and you cannot switch existing built-in tables to this plan. You'd need to create a new custom table with your desired schema and the Auxiliary pricing tier.

Related document:

Logs Ingestion API in Azure Monitor - Azure Monitor | Microsoft Learn

https://v4.hkg1.meaqua.org/en-us/azure/azure-monitor/logs/create-custom-table-auxiliary

If you found the comment/answer helpful, please consider clicking "Upvote it/accept the answer".

Thanks,

Siva shunmugam.
Jan Buijnsters 25 Reputation points

2025-12-11T08:31:13.7033333+00:00

@Siva shunmugam Nadessin What is the reasoning for making it impossible to switch an existing table from Basic to the Auxiliary plan?
Or is this something planned to be implemented on the Roadmap, and if so what is the expected release date?

Thanks,
Kind regards,
Jan

1 answer

Your answer

Siva shunmugam Nadessin 3,425 Reputation points Microsoft External Staff Moderator

2025-08-07T00:15:05.6+00:00

Hello mrcode,

For your question below are the answers

1.I’ve read the documentation on how to create a custom table with the Auxiliary pricing tier - but how do I send my Application Insights logs to this custom table instead of AppTraces?

Since Application Insights typically sends logs to the built- in AppTraces table, you will need to use the Logs Ingestion API to send your logs directly to the custom table you have created with the Auxiliary plan. This involves:

Creating a custom table with the Auxiliary plan.

Setting up a data collection rule and using the Logs Ingestion API to send your logs to the custom table. The custom table must have the right schema set up before you can ingest data into it. You can find detailed steps regarding the ingestion API, refer the documentation.

2. Is it possible to change the pricing tier of the AppTraces table to Auxiliary? Or do I need to create a new table with the same structure?

Unfortunately, you cannot change the pricing tier of the AppTraces table to Auxiliary. The Auxiliary plan is only supported on custom tables created via the API, and you cannot switch existing built-in tables to this plan. You'd need to create a new custom table with your desired schema and the Auxiliary pricing tier.

Related document:

Logs Ingestion API in Azure Monitor - Azure Monitor | Microsoft Learn

https://v4.hkg1.meaqua.org/en-us/azure/azure-monitor/logs/create-custom-table-auxiliary

If you found the comment/answer helpful, please consider clicking "Upvote it/accept the answer".

Thanks,

Siva shunmugam.
Jan Buijnsters 25 Reputation points

2025-12-11T08:31:13.7033333+00:00

@Siva shunmugam Nadessin What is the reasoning for making it impossible to switch an existing table from Basic to the Auxiliary plan?
Or is this something planned to be implemented on the Roadmap, and if so what is the expected release date?

Thanks,
Kind regards,
Jan

Answer 1

Hello mrcode,

The reason you cannot switch an existing table from Basic to Auxiliary in Azure Log Analytics is due to design and architectural constraints of the Auxiliary plan. Here’s the detailed reasoning:

1. Auxiliary Plan Is Only Supported at Table Creation

The Auxiliary plan is intended for low-cost ingestion and retention of verbose or compliance logs.
It is only available for new custom tables created via the API and cannot be applied to built-in Azure tables or existing tables.
Once a table is created with Auxiliary, its plan is immutable. This is explicitly documented: “Setting up a table with the Auxiliary plan is only supported on new tables. After you create a table with an Auxiliary plan, you can't switch the table's plan.”

2. Schema and Query Model Differences

· Auxiliary tables have different schema constraints (e.g., no dynamic columns) and optimized storage format for cost efficiency.

· They use Delta Parquet-based storage for batch processing, which is fundamentally different from the indexed storage used by Analytics/Basic tables.

· Switching plans would require rebuilding the table and re-ingesting data, which could break queries, alerts, and compliance guarantees.

3. Performance and Feature Trade-offs

Auxiliary tables are designed for cheap storage and slower queries, not for real-time analytics.
If Microsoft allowed switching, existing data would need to be transformed to match Auxiliary’s limitations (e.g., reduced query performance, limited KQL operators), which could lead to data integrity and feature compatibility issues.

4. Cost and Compliance Considerations

Auxiliary plan targets high-volume, low-touch logs for compliance and auditing.
Allowing conversion could create billing inconsistencies and compliance risks, as retention and query capabilities differ significantly between plans.

Current Options

You can switch between Analytics and Basic plans for supported tables once per week.
For Auxiliary, you must create a new custom table and redirect ingestion via Data Collection Rules (DCR) or the Logs ingestion API.

Roadmap

As of now, Microsoft has not announced support for converting existing tables to Auxiliary. This limitation is by design and documented in official guidance.

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How to send Application Insights logs to a custom table with Auxiliary pricing tier in Log Analytics

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