Data Sources

Dremio supports a variety of data sources, including NoSQL databases, relational databases, Hadoop, local filesystems, and cloud storage.

[warning] IMPORTANT

Case-sensitive source data file/table names are not supported.

In Dremio, data filenames in your data source are "seen" in a case-insensitive manner. So, if you have to three (3) file names with difference cases (for example, JOE Joe, and joe), Dremio "sees" the files as having the same name. Thus, searching on Joe, JOE, or joe, can result in unanticipated data results.

In addition, column names within a table that have the same name with different cases are not supported. For example, if two (2) columns named Trip_Pickup_DateTime and trip_pickup_datetime exist in the table, one of the columns may disappear when the header is extracted.

Files and Directories

Relational databases

Dremio enables users to run external queries, queries that use the native syntax of the relational database, to process SQL statements that are not yet supported by Dremio or are too complex to convert. Dremio administrators enable the feature for each data source and specify which Dremio users can edit that source. See External Queries for more information.

Dremio improves query performance for relational database datasets with Runtime Filtering, which applies dimension table filters to joined fact tables at runtime.

[info]
Decimal Support
As of Dremio 4.0, decimal-to-decimal mappings are supported for relational database sources.

Collation

Relational database sources must have a collation equivalent to LATIN1_GENERAL_BIN2 to ensure consistent results when operations are pushed down. For non-equivalent collations, create a view that coerces the collation to one that is equivalent to LATIN1_GENERAL_BIN2 and access that view.

Distributed Filesystems

NoSQL & Hadoop


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