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Consistently getting [ErrorCode: INTERNAL_ERROR_QUERY_ENGINE] after adding a new UNION to a view

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Hello,

I'm trying to run a view that is made of 3 UNIONs (so four SELECT statements in total). I noticed that after adding the last UNION SELECT statement, the view no longer runs and I get the "[ErrorCode: INTERNAL_ERROR_QUERY_ENGINE] Amazon Athena experienced an internal error while executing this query. Please contact AWS support for further assistance. You will not be charged for this query. We apologize for the inconvenience." error.

What is funny to me is that all the individual SELECT blocks run properly without errors. Furthermore, the error just started occurring after I added the fourth UNION. It's also interesting that whenever I remove any of the UNION SELECT statements (doesn't matter which one), the view runs normally without any errors.

Is there some sort of UNION limit in Athena or something that I'm missing?

Thanks in advance!

gefragt vor einem Jahr577 Aufrufe
1 Antwort
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Akzeptierte Antwort

Hello Ciciliati,

Amazon Athena does have some limitations on the complexity and size of queries that can be executed. While there is no explicit limit on the number of UNIONs you can use in a query, you may be hitting other limits or encountering query optimization issues. The "[ErrorCode: INTERNAL_ERROR_QUERY_ENGINE]" error is a generic error message that indicates an internal issue with Athena's query execution engine.

Here are a few possible reasons for the error you're encountering:

  1. Query Complexity: The query complexity and resource requirements increase with the number of UNIONs, especially if the individual SELECT statements are complex. Athena may be struggling to optimize and execute the query due to its complexity.

  2. Data Volume: Large data volumes can lead to resource exhaustion, resulting in this error. If your query processes a substantial amount of data, it may require more memory and CPU resources than are available for your query.

  3. Query Optimization: Athena's query optimizer may have difficulty optimizing a complex query with multiple UNIONs. Query optimization is a complex process, and sometimes, certain query patterns can lead to suboptimal execution plans.

To resolve this issue, consider the following steps:

  1. Optimize Query: Review your query and see if there are ways to simplify it or make it more efficient. Ensure that you have appropriate filters and predicates to reduce the data volume processed by the query.

  2. Pagination: If your query processes a large amount of data, consider adding pagination to retrieve smaller chunks of data at a time rather than processing everything in a single query.

  3. Data Partitioning: If your data is stored in a format like Parquet or ORC, consider partitioning your data to improve query performance. Partitioning can significantly reduce the amount of data scanned during queries.

  4. Resource Allocation: Check the resource allocation for your Athena query. You can adjust the query execution settings to allocate more memory or increase the query timeout if necessary.

  5. Query Simplification: If the UNIONs are causing the issue, try to simplify your query by using fewer UNIONs or reorganizing your data to reduce the need for UNION operations.

  6. AWS Support: If the issue persists and you've ruled out query complexity and data volume as the primary causes, it may be worth reaching out to AWS Support for further assistance. They can investigate the specific error and provide guidance on how to optimize your query for successful execution.

AWS Athena is designed to handle a wide range of query workloads, but complex queries or large datasets may require additional optimization and resource allocation to ensure smooth execution.

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beantwortet vor einem Jahr
  • Thank you for the thorough response Gabriel, I'll make sure to review the query and see what can be done to improve the performance!

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