How to rename a column in Databricks

6
votes

How do you rename a column in Databricks?

The following does not work:

ALTER TABLE mySchema.myTable change COLUMN old_name new_name int

It returns the error:

ALTER TABLE CHANGE COLUMN is not supported for changing column 'old_name' with type 'IntegerType >(nullable = true)' to 'new_name' with type 'IntegerType (nullable = true)';

If it makes a difference, this table is using Delta Lake, and it is NOT partitioned or z-ordered by this "old_name" column.

2
databricksdelta-lake

2 Answers

13
votes

You can't rename or change a column datatype in Databricks, only add new columns, reorder them or add column comments. To do this you must rewrite the table using the overwriteSchema option.

Take this example below from this documentation:

spark.read.table(...)
  .withColumnRenamed("date", "date_created")
  .write
  .mode("overwrite")
  .option("overwriteSchema", "true")
  .table(...)
3
votes

To be able to rename the column, overwriteSchema with saveAsTable should be used:

spark.read.table(Table_Name)
  .withColumnRenamed("currentName", "newName")
  .write
  .format("delta")
  .mode("overwrite")
  .option("overwriteSchema", "true")
  .saveAsTable( Table_Name )