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Posted to reviews@spark.apache.org by "allisonwang-db (via GitHub)" <gi...@apache.org> on 2023/08/17 21:03:02 UTC
[GitHub] [spark] allisonwang-db commented on a diff in pull request #42420: [SPARK-44748][SQL] Query execution for the PARTITION BY clause in UDTF TABLE arguments
allisonwang-db commented on code in PR #42420:
URL: https://github.com/apache/spark/pull/42420#discussion_r1297730442
##########
python/pyspark/worker.py:
##########
@@ -573,9 +574,73 @@ def read_udtf(pickleSer, infile, eval_type):
f"The return type of a UDTF must be a struct type, but got {type(return_type)}."
)
+ class UDTFWithPartitions:
+ """
+ This implements the logic of a UDTF that accepts an input TABLE argument with one or more
+ PARTITION BY expressions.
Review Comment:
It would be extremely helpful if we can add an example here. Maybe something like
-- t: [c1, c2]
SELECT * FROM my_udtf(TABLE (t) PARTITION BY .. ORDER BY ..)
partition_child_indexes in this case will be ...
##########
python/pyspark/worker.py:
##########
@@ -573,9 +574,73 @@ def read_udtf(pickleSer, infile, eval_type):
f"The return type of a UDTF must be a struct type, but got {type(return_type)}."
)
+ class UDTFWithPartitions:
+ """
+ This implements the logic of a UDTF that accepts an input TABLE argument with one or more
+ PARTITION BY expressions.
+
+ Parameters
+ ----------
+ create_udtf: function
+ Function to create a new instance of the UDTF to be invoked.
+ partition_child_indexes: list
+ List of integers identifying zero-based indexes of the columns of the input table that
+ contain projected partitioning expressions. This class will inspect these values for
+ each pair of consecutive input rows. When they change, this indicates the boundary
+ between two partitions, and we will invoke the 'terminate' method on the UDTF class
+ instance and then destroy it and create a new one to implement the desired partitioning
+ semantics.
+ """
+ def __init__(self, create_udtf, partition_child_indexes):
Review Comment:
nit: can we add type hint here?
##########
python/pyspark/worker.py:
##########
@@ -573,9 +574,73 @@ def read_udtf(pickleSer, infile, eval_type):
f"The return type of a UDTF must be a struct type, but got {type(return_type)}."
)
+ class UDTFWithPartitions:
+ """
+ This implements the logic of a UDTF that accepts an input TABLE argument with one or more
+ PARTITION BY expressions.
+
+ Parameters
+ ----------
+ create_udtf: function
+ Function to create a new instance of the UDTF to be invoked.
+ partition_child_indexes: list
+ List of integers identifying zero-based indexes of the columns of the input table that
+ contain projected partitioning expressions. This class will inspect these values for
+ each pair of consecutive input rows. When they change, this indicates the boundary
+ between two partitions, and we will invoke the 'terminate' method on the UDTF class
+ instance and then destroy it and create a new one to implement the desired partitioning
+ semantics.
+ """
+ def __init__(self, create_udtf, partition_child_indexes):
+ self._create_udtf = create_udtf
+ self._udtf = create_udtf()
+ self._prev_arguments = None
+ self._partition_child_indexes = partition_child_indexes
+
+ def eval(self, *args, **kwargs):
+ changed_partitions = self._check_partition_boundaries(
+ list(args) + list(kwargs.values()))
+ if changed_partitions:
+ if self._udtf.terminate is not None:
+ result = self._udtf.terminate()
+ if result is not None:
+ for row in result:
+ yield row
+ self._udtf = self._create_udtf()
+ if self._udtf.eval is not None:
+ result = self._udtf.eval(*args, **kwargs)
+ if result is not None:
+ for row in result:
+ yield row
+
+ def terminate(self):
+ if self._udtf.terminate is not None:
+ return self._udtf.terminate()
+
+ def _check_partition_boundaries(self, arguments):
+ result = False
Review Comment:
nit: can we add type hinting for the function input and output, and docstring comments? And also for _get_table_arg?
##########
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala:
##########
@@ -2118,11 +2121,32 @@ class Analyzer(override val catalogManager: CatalogManager) extends RuleExecutor
tableArgs.size)
}
val alias = SubqueryAlias.generateSubqueryName(s"_${tableArgs.size}")
+ // Propagate the column indexes for TABLE arguments to the PythonUDTF instance.
+ val tvfWithTableColumnIndexes: LogicalPlan = tvf match {
+ case g @ Generate(p: PythonUDTF, _, _, _, _, _) =>
+ functionTableSubqueryArgs.headOption.map { tableArg =>
+ val indexes = PythonUDTFPartitionColumnIndexes(
+ tableArg.partitioningExpressionIndexes)
+ g.copy(generator = p.copy(pythonUDTFPartitionColumnIndexes = Some(indexes)))
+ }.getOrElse {
+ g
+ }
+ case g @ Generate(p: UnresolvedPolymorphicPythonUDTF, _, _, _, _, _) =>
+ functionTableSubqueryArgs.headOption.map { tableArg =>
+ val indexes = PythonUDTFPartitionColumnIndexes(
+ tableArg.partitioningExpressionIndexes)
+ g.copy(generator = p.copy(pythonUDTFPartitionColumnIndexes = Some(indexes)))
+ }.getOrElse {
+ g
Review Comment:
We can combine this with the one above:
```
p : (PythonUDTF | UnresolvedPolymorphicPythonUDTF)
```
##########
sql/core/src/main/scala/org/apache/spark/sql/execution/python/BatchEvalPythonUDTFExec.scala:
##########
@@ -134,6 +134,13 @@ object PythonUDTFRunner {
dataOut.writeBoolean(false)
}
}
+ udtf.pythonUDTFPartitionColumnIndexes match {
+ case Some(partitionColumnIndexes) =>
+ dataOut.writeInt(partitionColumnIndexes.partitionChildIndexes.length)
+ partitionColumnIndexes.partitionChildIndexes.foreach(dataOut.writeInt)
Review Comment:
can we assert partitionColumnIndexes.partitionChildIndexes.length > 0 here?
##########
python/pyspark/worker.py:
##########
@@ -573,9 +574,73 @@ def read_udtf(pickleSer, infile, eval_type):
f"The return type of a UDTF must be a struct type, but got {type(return_type)}."
)
+ class UDTFWithPartitions:
+ """
+ This implements the logic of a UDTF that accepts an input TABLE argument with one or more
+ PARTITION BY expressions.
+
+ Parameters
+ ----------
+ create_udtf: function
+ Function to create a new instance of the UDTF to be invoked.
+ partition_child_indexes: list
+ List of integers identifying zero-based indexes of the columns of the input table that
+ contain projected partitioning expressions. This class will inspect these values for
+ each pair of consecutive input rows. When they change, this indicates the boundary
+ between two partitions, and we will invoke the 'terminate' method on the UDTF class
+ instance and then destroy it and create a new one to implement the desired partitioning
+ semantics.
+ """
+ def __init__(self, create_udtf, partition_child_indexes):
+ self._create_udtf = create_udtf
+ self._udtf = create_udtf()
+ self._prev_arguments = None
+ self._partition_child_indexes = partition_child_indexes
+
+ def eval(self, *args, **kwargs):
+ changed_partitions = self._check_partition_boundaries(
+ list(args) + list(kwargs.values()))
+ if changed_partitions:
+ if self._udtf.terminate is not None:
+ result = self._udtf.terminate()
+ if result is not None:
+ for row in result:
+ yield row
Review Comment:
I wonder if this will cause issues when we join the output rows from the UDTF with the input rows. Here is how we join the rows:
```
input_row_1 -> [eval_output_row_1, eval_output_row_2, .. ]
input_row_2 - >[eval_output_row_1, ..]
(now assume we consumed all input rows in a partition, input_row_2 is the last one)
(we use the last row in a partition to join with the rows generated by terminate)
input_row_2 -> [terminate_output_row_1, terminate_output_row_2, ...]
```
If we directly yield rows from `terminate` here, will they be joined with the input row from the next partition?
##########
python/pyspark/worker.py:
##########
@@ -573,9 +574,73 @@ def read_udtf(pickleSer, infile, eval_type):
f"The return type of a UDTF must be a struct type, but got {type(return_type)}."
)
+ class UDTFWithPartitions:
+ """
+ This implements the logic of a UDTF that accepts an input TABLE argument with one or more
+ PARTITION BY expressions.
+
+ Parameters
+ ----------
+ create_udtf: function
+ Function to create a new instance of the UDTF to be invoked.
+ partition_child_indexes: list
+ List of integers identifying zero-based indexes of the columns of the input table that
+ contain projected partitioning expressions. This class will inspect these values for
+ each pair of consecutive input rows. When they change, this indicates the boundary
+ between two partitions, and we will invoke the 'terminate' method on the UDTF class
+ instance and then destroy it and create a new one to implement the desired partitioning
+ semantics.
Review Comment:
I think these should be under `__init__`?
```
def __init__(self, ..):
"""
docstring here
"""
```
##########
python/pyspark/worker.py:
##########
@@ -573,9 +574,73 @@ def read_udtf(pickleSer, infile, eval_type):
f"The return type of a UDTF must be a struct type, but got {type(return_type)}."
)
+ class UDTFWithPartitions:
+ """
+ This implements the logic of a UDTF that accepts an input TABLE argument with one or more
+ PARTITION BY expressions.
+
+ Parameters
+ ----------
+ create_udtf: function
+ Function to create a new instance of the UDTF to be invoked.
+ partition_child_indexes: list
+ List of integers identifying zero-based indexes of the columns of the input table that
+ contain projected partitioning expressions. This class will inspect these values for
+ each pair of consecutive input rows. When they change, this indicates the boundary
+ between two partitions, and we will invoke the 'terminate' method on the UDTF class
+ instance and then destroy it and create a new one to implement the desired partitioning
+ semantics.
+ """
+ def __init__(self, create_udtf, partition_child_indexes):
+ self._create_udtf = create_udtf
+ self._udtf = create_udtf()
+ self._prev_arguments = None
+ self._partition_child_indexes = partition_child_indexes
+
+ def eval(self, *args, **kwargs):
+ changed_partitions = self._check_partition_boundaries(
+ list(args) + list(kwargs.values()))
+ if changed_partitions:
+ if self._udtf.terminate is not None:
+ result = self._udtf.terminate()
+ if result is not None:
+ for row in result:
+ yield row
+ self._udtf = self._create_udtf()
Review Comment:
note: we should probably add some metrics here on how many times this udtf instance is created.
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