Promoting Entities

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

[info] 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.

[info] 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.".

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