UnresolvedRelation Leaf Logical Operator for Table Reference¶

[[tableIdentifier]][[creating-instance]] UnresolvedRelation is a LeafNode.md[leaf logical operator] to represent a table reference in a logical query plan that has yet to be resolved (i.e. looked up in a catalog).

[NOTE]¶

If after Logical Analyzer has finished analyzing a logical query plan the plan has still a UnresolvedRelation it spark-sql-Analyzer-CheckAnalysis.md#UnresolvedRelation[fails the analyze phase] with the following AnalysisException:

Table or view not found: [tableIdentifier]

¶

UnresolvedRelation is <> when:

• SparkSession is requested to SparkSession.md#table[create a DataFrame from a table]

• DataFrameWriter is requested to insert a DataFrame into a table

• INSERT INTO (TABLE) or INSERT OVERWRITE TABLE SQL commands are executed

• CreateHiveTableAsSelectCommand logical command is executed

[TIP]¶

Use table operator from Catalyst DSL to create a UnresolvedRelation logical operator, e.g. for testing or Spark SQL internals exploration.

[source, scala]¶

import org.apache.spark.sql.catalyst.dsl.plans._ val plan = table(db = "myDB", ref = "t1") scala> println(plan.numberedTreeString) 00 'UnresolvedRelation myDB.t1

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NOTE: UnresolvedRelation is resolved to...FIXME