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Denodo doesn't push down nest function into source while caching

Hi All, I have an impala data source and I connect to it using JDBC in Denodo. While applying caching on a derived view contains a column that's an array of some other columns using nest function, I got this message in the execution plan: **Denodo doesn't push down nest function into source while caching** I tried on a http data source and it worked fine, Is there a problem with JDBC to delegate the nest function? Thanks.
user
25-02-2024 02:10:04 -0500
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1 Answer

Hi, In general, **Denodo doesn't push down nest function into source while caching** indicates that the function cannot be delegated to the source. The NEST function is native to Denodo and does not have an equivalent function in Impala. I would use custom functions to accommodate the NEST logic and to delegate to the underlying data source. You could refer to [Developing Custom Functions](https://community.denodo.com/docs/html/browse/8.0/en/vdp/developer/developing_extensions/developing_custom_functions/creating_custom_functions_with_annotations#developing-custom-functions-that-can-be-delegated-to-a-database) section of the Virtual DataPort Developer Guide for more details. If you still need further assistance and if you are a valid support user, you can raise a [Support Case](https://support.denodo.com/cases/add), for further assistance from the support team. Hope this helps!
Denodo Team
27-02-2024 06:48:16 -0500
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