![]() ![]() ![]() If there are multiple whenMatched clauses, then they are evaluated in the order they are specified. If this clause condition exists, the update or delete action is executed for any matching source-target row pair only when the clause condition is true. The delete action deletes the matched row.Įach whenMatched clause can have an optional condition. The update action in merge only updates the specified columns (similar to the update operation) of the matched target row. WhenMatched clauses can have at most one update and one delete action. These clauses have the following semantics. WhenMatched clauses are executed when a source row matches a target table row based on the match condition. There can be any number of whenMatched and whenNotMatched clauses. Here is a detailed description of the merge programmatic operation. See the Delta Lake APIs for Scala, Java, and Python syntax details. ![]() as ( "updates" ), "people.id = updates.id" ). load ( "/tmp/delta/people-10m-updates" ) deltaTable. forPath ( spark, "/tmp/delta/people-10m" ) Dataset dfUpdates = spark. Import io.delta.tables.* import .functions import DeltaTable deltaTable = DeltaTable. insertExpr ( Map ( "id" -> "updates.id", "firstName" -> "updates.firstName", "middleName" -> "updates.middleName", "lastName" -> "updates.lastName", "gender" -> "updates.gender", "birthDate" -> "updates.birthDate", "ssn" -> "updates.ssn", "salary" -> "updates.salary" )). updateExpr ( Map ( "id" -> "updates.id", "firstName" -> "updates.firstName", "middleName" -> "updates.middleName", "lastName" -> "updates.lastName", "gender" -> "updates.gender", "birthDate" -> "updates.birthDate", "ssn" -> "updates.ssn", "salary" -> "updates.salary" )). forPath ( spark, "tmp/delta/people-10m-updates" ) val dfUpdates = deltaTablePeopleUpdates. forPath ( spark, "/tmp/delta/people-10m" ) val deltaTablePeopleUpdates = DeltaTable. Access Delta tables from external data processing engines.How does Delta Lake manage feature compatibility?.Upsert from streaming queries using foreachBatch.Slowly changing data (SCD) Type 2 operation into Delta tables.Data deduplication when writing into Delta tables.Special considerations for schemas that contain arrays of structs. ![]()
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