class DeltaMergeBuilder extends AnalysisHelper with Logging

Builder to specify how to merge data from source DataFrame into the target Delta table. You can specify any number of whenMatched and whenNotMatched clauses. Here are the constraints on these clauses.

  • whenMatched clauses:
    • There can be at most one update action and one delete action in whenMatched clauses.
    • Each whenMatched clause can have an optional condition. However, if there are two whenMatched clauses, then the first one must have a condition.
    • When there are two whenMatched clauses and there are conditions (or the lack of) such that a row matches both clauses, then the first clause/action is executed. In other words, the order of the whenMatched clauses matter.
    • If none of the whenMatched clauses match a source-target row pair that satisfy the merge condition, then the target rows will not be updated or deleted.
    • If you want to update all the columns of the target Delta table with the corresponding column of the source DataFrame, then you can use the whenMatched(...).updateAll(). This is equivalent to 
              whenMatched(...).updateExpr(Map(
          ("col1", "source.col1"),
          ("col2", "source.col2"),
          ...))
  • whenNotMatched clauses:
    • This clause can have only an insert action, which can have an optional condition.
    • If the whenNotMatched clause is not present or if it is present but the non-matching source row does not satisfy the condition, then the source row is not inserted.
    • If you want to insert all the columns of the target Delta table with the corresponding column of the source DataFrame, then you can use whenMatched(...).insertAll(). This is equivalent to 
              whenMatched(...).insertExpr(Map(
          ("col1", "source.col1"),
          ("col2", "source.col2"),
          ...))

Scala example to update a key-value Delta table with new key-values from a source DataFrame:

deltaTable
 .as("target")
 .merge(
   source.as("source"),
   "target.key = source.key")
 .whenMatched
 .updateExpr(Map(
   "value" -> "source.value"))
 .whenNotMatched
 .insertExpr(Map(
   "key" -> "source.key",
   "value" -> "source.value"))
 .execute()

Java example to update a key-value Delta table with new key-values from a source DataFrame:

deltaTable
 .as("target")
 .merge(
   source.as("source"),
   "target.key = source.key")
 .whenMatched
 .updateExpr(
    new HashMap<String, String>() {{
      put("value", "source.value");
    }})
 .whenNotMatched
 .insertExpr(
    new HashMap<String, String>() {{
     put("key", "source.key");
     put("value", "source.value");
   }})
 .execute();
Since

0.3.0

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Inherited
  1. DeltaMergeBuilder
  2. Logging
  3. AnalysisHelper
  4. AnyRef
  5. Any
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Value Members

  1. def execute(): Unit

    Execute the merge operation based on the built matched and not matched actions.

    Execute the merge operation based on the built matched and not matched actions.

    Since

    0.3.0

  2. def whenMatched(condition: Column): DeltaMergeMatchedActionBuilder

    Build the actions to perform when the merge condition was matched and the given condition is true.

    Build the actions to perform when the merge condition was matched and the given condition is true. This returns a DeltaMergeMatchedActionBuilder object which can be used to specify how to update or delete the matched target table row with the source row.

    condition

    boolean expression as a Column object

    Since

    0.3.0

  3. def whenMatched(condition: String): DeltaMergeMatchedActionBuilder

    Build the actions to perform when the merge condition was matched and the given condition is true.

    Build the actions to perform when the merge condition was matched and the given condition is true. This returns DeltaMergeMatchedActionBuilder object which can be used to specify how to update or delete the matched target table row with the source row.

    condition

    boolean expression as a SQL formatted string

    Since

    0.3.0

  4. def whenMatched(): DeltaMergeMatchedActionBuilder

    Build the actions to perform when the merge condition was matched.

    Build the actions to perform when the merge condition was matched. This returns DeltaMergeMatchedActionBuilder object which can be used to specify how to update or delete the matched target table row with the source row.

    Since

    0.3.0

  5. def whenNotMatched(condition: Column): DeltaMergeNotMatchedActionBuilder

    Build the actions to perform when the merge condition was not matched and the given condition is true.

    Build the actions to perform when the merge condition was not matched and the given condition is true. This returns DeltaMergeMatchedActionBuilder object which can be used to specify how to insert the new sourced row into the target table.

    condition

    boolean expression as a Column object

    Since

    0.3.0

  6. def whenNotMatched(condition: String): DeltaMergeNotMatchedActionBuilder

    Build the actions to perform when the merge condition was not matched and the given condition is true.

    Build the actions to perform when the merge condition was not matched and the given condition is true. This returns DeltaMergeMatchedActionBuilder object which can be used to specify how to insert the new sourced row into the target table.

    condition

    boolean expression as a SQL formatted string

    Since

    0.3.0

  7. def whenNotMatched(): DeltaMergeNotMatchedActionBuilder

    Build the action to perform when the merge condition was not matched.

    Build the action to perform when the merge condition was not matched. This returns DeltaMergeNotMatchedActionBuilder object which can be used to specify how to insert the new sourced row into the target table.

    Since

    0.3.0