[SPARK-11875][ML][PYSPARK] Update doc for PySpark HasCheckpointInterval

* Update doc for PySpark ```HasCheckpointInterval``` that users can understand how to disable checkpoint.
* Update doc for PySpark ```cacheNodeIds``` of ```DecisionTreeParams``` to notify the relationship between ```cacheNodeIds``` and ```checkpointInterval```.

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #9856 from yanboliang/spark-11875.

1 files changed, 4 insertions, 2 deletions

diff --git a/python/pyspark/ml/param/_shared_params_code_gen.py b/python/pyspark/ml/param/_shared_params_code_gen.py
index 070c5db01a..0528dc1e3a 100644
--- a/python/pyspark/ml/param/_shared_params_code_gen.py
+++ b/python/pyspark/ml/param/_shared_params_code_gen.py
@@ -118,7 +118,8 @@ if __name__ == "__main__":
         ("inputCols", "input column names.", None),
         ("outputCol", "output column name.", "self.uid + '__output'"),
         ("numFeatures", "number of features.", None),
-        ("checkpointInterval", "checkpoint interval (>= 1).", None),
+        ("checkpointInterval", "set checkpoint interval (>= 1) or disable checkpoint (-1). " +
+         "E.g. 10 means that the cache will get checkpointed every 10 iterations.", None),
         ("seed", "random seed.", "hash(type(self).__name__)"),
         ("tol", "the convergence tolerance for iterative algorithms.", None),
         ("stepSize", "Step size to be used for each iteration of optimization.", None),
@@ -157,7 +158,8 @@ if __name__ == "__main__":
         ("maxMemoryInMB", "Maximum memory in MB allocated to histogram aggregation."),
         ("cacheNodeIds", "If false, the algorithm will pass trees to executors to match " +
          "instances with nodes. If true, the algorithm will cache node IDs for each instance. " +
-         "Caching can speed up training of deeper trees.")]
+         "Caching can speed up training of deeper trees. Users can set how often should the " +
+         "cache be checkpointed or disable it by setting checkpointInterval.")]
 
     decisionTreeCode = '''class DecisionTreeParams(Params):
     """