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RelationProvider — Relations with Pre-Defined Schema

RelationProvider is an abstraction of providers for relational data sources with schema inference (schema discovery). In other words, the schema of a relation is pre-defined (fixed), and a user-specified schema is not allowed.

SchemaRelationProvider

Use SchemaRelationProvider for data source providers that require a user-defined schema.

Contract

Creating BaseRelation

createRelation(
  sqlContext: SQLContext,
  parameters: Map[String, String]): BaseRelation

Creates a BaseRelation

Used when:

Implementations

CreatableRelationProvider

It is a common pattern while developing a custom data source to use RelationProvider.createRelation with CreatableRelationProvider when requested for a relation (after writing out a structured query).

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