Time Travel¶

Time Travel allows SQL queries to use an optional version or timestamp in table identifiers:

FOR? (SYSTEM_VERSION | VERSION) AS OF version
FOR? (SYSTEM_TIME | TIMESTAMP) AS OF timestamp

RelationTimeTravel logical operator is used to represent time-travel table specification in a logical query plan.

At resolution phase, a session CatalogPlugin is requested to load a versioned table.

Versioned Tables Unsupported¶

TableCatalog throws a NoSuchTableException exception when requested to look up a versioned table.

org.apache.spark.sql.AnalysisException: [UNSUPPORTED_FEATURE.TIME_TRAVEL] The feature is not supported: Time travel on the relation: `spark_catalog`.`default`.`time_travel_demo`.
  at org.apache.spark.sql.errors.QueryCompilationErrors$.timeTravelUnsupportedError(QueryCompilationErrors.scala:3285)
  at org.apache.spark.sql.execution.datasources.v2.V2SessionCatalog.failTimeTravel(V2SessionCatalog.scala:95)
  at org.apache.spark.sql.execution.datasources.v2.V2SessionCatalog.loadTable(V2SessionCatalog.scala:87)
  at org.apache.spark.sql.connector.catalog.CatalogV2Util$.getTable(CatalogV2Util.scala:350)
  at org.apache.spark.sql.connector.catalog.CatalogV2Util$.loadTable(CatalogV2Util.scala:336)
  at org.apache.spark.sql.catalyst.analysis.Analyzer$ResolveRelations$.$anonfun$resolveRelation$3(Analyzer.scala:1268)

The decision how to load a versioned table is left to custom TableCatalogs (e.g. Delta Lake).

scala> println(io.delta.VERSION)
3.0.0

scala> sql("create table time_travel_demo (id long) using delta")

scala> sql("select * from time_travel_demo version as of 0").show()
+---+
| id|
+---+
+---+

Temporary Views Unsupported¶

Time travel is not supported on temporary views (as enforced by ResolveRelations logical analysis rule).