diff options
Diffstat (limited to 'mllib')
| -rw-r--r-- | mllib/src/main/scala/org/apache/spark/ml/feature/SQLTransformer.scala | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/mllib/src/main/scala/org/apache/spark/ml/feature/SQLTransformer.scala b/mllib/src/main/scala/org/apache/spark/ml/feature/SQLTransformer.scala index 3a735017ba..c09f4d076c 100644 --- a/mllib/src/main/scala/org/apache/spark/ml/feature/SQLTransformer.scala +++ b/mllib/src/main/scala/org/apache/spark/ml/feature/SQLTransformer.scala @@ -27,9 +27,16 @@ import org.apache.spark.sql.types.StructType /** * :: Experimental :: - * Implements the transforms which are defined by SQL statement. - * Currently we only support SQL syntax like 'SELECT ... FROM __THIS__' + * Implements the transformations which are defined by SQL statement. + * Currently we only support SQL syntax like 'SELECT ... FROM __THIS__ ...' * where '__THIS__' represents the underlying table of the input dataset. + * The select clause specifies the fields, constants, and expressions to display in + * the output, it can be any select clause that Spark SQL supports. Users can also + * use Spark SQL built-in function and UDFs to operate on these selected columns. + * For example, [[SQLTransformer]] supports statements like: + * - SELECT a, a + b AS a_b FROM __THIS__ + * - SELECT a, SQRT(b) AS b_sqrt FROM __THIS__ where a > 5 + * - SELECT a, b, SUM(c) AS c_sum FROM __THIS__ GROUP BY a, b */ @Experimental @Since("1.6.0") |