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    Promoting Entities

    This topic describes the behaviour associated with promoting entities such as files and folders.

    note:

    Not Supported: Promoting folders with non-homogenous file types is not supported.

    Default Behaviour

    When you issue queries against files or folders, the default behavior is to not auto-promote files/folders to datasets. For example, given a MAPRFS source with a Root: [folder | file] structure, if you executed select * from MAPRFS.folder.file, the query fails.

    note:

    Previous Auto-Promote Behaviour:

    Prior to Dremio version 3.0, Dremio’s default behavior for filesystem-based sources (HDFS, S3, NAS, etc) was to automatically auto-promote a folder or file to a dataset when you run a query on a file or folder.

    For example, given a MAPRFS source with a Root: [folder | file] structure, if you executed select * from MAPRFS.folder.file, the file would automatically be promoted to a dataset.

    Auto-Promoting Entities

    If you want to automatically promote files when queries are issued against the file or folder,

    1. Edit your source.
    2. Navigate to Edit Source > Metadata > Dataset Handling.
    3. Select “Automatically format files into physical datasets when users issue queries.”.