vibhatha commented on a change in pull request #12033:
URL: https://github.com/apache/arrow/pull/12033#discussion_r781965392
##########
File path: docs/source/cpp/streaming_execution.rst
##########
@@ -305,3 +305,451 @@ Datasets may be scanned multiple times; just make
multiple scan
nodes from that dataset. (Useful for a self-join, for example.)
Note that producing two scan nodes like this will perform all
reads and decodes twice.
+
+Constructing ``ExecNode`` using Options
+=======================================
+
+Using the execution plan we can construct various queries.
+To construct such queries, we have provided a set of building blocks
+referred to as :class:`ExecNode` s. These nodes provide the ability to
+construct operations like filtering, projection, join, etc.
+
+This is the list of operations associated with the execution plan;
+
+.. list-table:: Operations and Options
+ :widths: 50 50
+ :header-rows: 1
+
+ * - Operation
+ - Options
+ * - ``source``
+ - :class:`arrow::compute::SourceNodeOptions`
+ * - ``filter``
+ - :class:`arrow::compute::FilterNodeOptions`
+ * - ``project``
+ - :class:`arrow::compute::ProjectNodeOptions`
+ * - ``aggregate``
+ - :class:`arrow::compute::ScalarAggregateOptions`
+ * - ``sink``
+ - :class:`arrow::compute::SinkNodeOptions`
+ * - ``consuming_sink``
+ - :class:`arrow::compute::ConsumingSinkNodeOptions`
+ * - ``order_by_sink``
+ - :class:`arrow::compute::OrderBySinkNodeOptions`
+ * - ``select_k_sink``
+ - :class:`arrow::compute::SelectKSinkNodeOptions`
+ * - ``scan``
+ - :class:`arrow::compute::ScanNodeOptions`
+ * - ``hash_join``
+ - :class:`arrow::compute::HashJoinNodeOptions`
+ * - ``write``
+ - :class:`arrow::dataset::WriteNodeOptions`
+ * - ``union``
+ - N/A
+
+
+.. _stream_execution_source_docs:
+
+``source``
+----------
+
+`source` operation can be considered as an entry point to create a streaming
execution plan.
+A source node can be constructed as follows.
+:class:`arrow::compute::SourceNodeOptions` are used to create the ``source``
operation.
+The :class:`Schema` of the data passing through and a function to generate
data
+``arrow::AsyncGenerator<arrow::util::optional<cp::ExecBatch>>``
+are required to create this option. Additionally, when using `source`
operator,
+the data scanning operations like filter and project may need to be applied
+in a later part of the execution plan.
+
+Struct to hold the data generator definition;
+
+.. literalinclude::
../../../cpp/examples/arrow/execution_plan_documentation_examples.cc
+ :language: cpp
+ :start-after: (Doc section: BatchesWithSchema Definition)
+ :end-before: (Doc section: BatchesWithSchema Definition)
+ :linenos:
+ :lineno-match:
+
+Generating Batches for computation;
+
+.. literalinclude::
../../../cpp/examples/arrow/execution_plan_documentation_examples.cc
+ :language: cpp
+ :start-after: (Doc section: MakeBasicBatches Definition)
+ :end-before: (Doc section: MakeBasicBatches Definition)
+ :linenos:
+ :lineno-match:
+
+Example of using ``source`` (usage of sink is explained in detail in
:ref:`sink<stream_execution_sink_docs>`);
+
+.. literalinclude::
../../../cpp/examples/arrow/execution_plan_documentation_examples.cc
+ :language: cpp
+ :start-after: (Doc section: Source Example)
+ :end-before: (Doc section: Source Example)
+ :linenos:
+ :lineno-match:
+
+.. _stream_execution_filter_docs:
+
+``filter``
+----------
+
+``filter`` operation as the name suggests, provides an option to define a data
filtering
+criteria. It keeps only rows matching a given expression.
+Filters can be written using :class:`arrow::compute::Expression`.
+For example, if we wish to keep rows of column ``b`` greater than 3,
+then we can use the following expression::, can be written using
+:class:`arrow::compute::FilterNodeOptions` as follows::
+
+ // a > 3
+ arrow::compute::Expression filter_opt = arrow::compute::greater(
+ arrow::compute::field_ref("a"),
+ arrow::compute::literal(3));
+
+Using this option, the filter node can be constructed as follows::
+
+ // creating filter node
+ arrow::compute::ExecNode* filter;
+ ARROW_ASSIGN_OR_RAISE(filter, arrow::compute::MakeExecNode("filter",
+ // plan
+ plan.get(),
+ // previous node
+ {scan},
+ //filter node options
+ arrow::compute::FilterNodeOptions{filter_opt}));
+
+Filter Example;
+
+.. literalinclude::
../../../cpp/examples/arrow/execution_plan_documentation_examples.cc
+ :language: cpp
+ :start-after: (Doc section: Filter Example)
+ :end-before: (Doc section: Filter Example)
+ :linenos:
+ :lineno-match:
+
+.. _stream_execution_project_docs:
+
+``project``
+-----------
+
+``project`` operation rearranges, deletes, transforms, and creates columns.
+Each output column is computed by evaluating an expression
+against the source record batch. This is exposed via
+:class:`arrow::compute::ProjectNodeOptions` class which requires,
+a :class:`arrow::compute::Expression`, names for the output columns (if names
are not
+provided, the string representations of exprs will be used).
+
+Sample Expression for projection::
+
+ // a * 2 (multiply values in a column by 2)
+ arrow::compute::Expression a_times_2 = arrow::compute::call("multiply",
+ {arrow::compute::field_ref("a"), arrow::compute::literal(2)});
+
+
+Creating a project node::
+
+ arrow::compute::ExecNode* project;
+ ARROW_ASSIGN_OR_RAISE(project,
+ arrow::compute::MakeExecNode("project",
+ // plan
+ plan.get(),
+ // previous node
+ {scan},
+ // project node options
+ arrow::compute::ProjectNodeOptions{{a_times_2}}));
+
+Project Example;
+
+.. literalinclude::
../../../cpp/examples/arrow/execution_plan_documentation_examples.cc
+ :language: cpp
+ :start-after: (Doc section: Project Example)
+ :end-before: (Doc section: Project Example)
+ :linenos:
+ :lineno-match:
+
+.. _stream_execution_aggregate_docs:
+
+``aggregate``
+-------------
+
+``aggregate`` operation provides various data aggregation options.
+The :class:`arrow::compute::AggregateNodeOptions` is used to
+define the aggregation criterion. These options can be
+selected from :ref:`aggregation options <aggregation-option-list>`.
+
+Example::
+
+ arrow::compute::IndexOptions index_options(arrow::MakeScalar("1"));
+
+An example for creating an aggregate node::
+
+ arrow::compute::CountOptions
options(arrow::compute::CountOptions::ONLY_VALID);
+
+ auto aggregate_options = arrow::compute::AggregateNodeOptions{
+ /*aggregates=*/{{"hash_count", &options}},
+ /*targets=*/{"a"},
+ /*names=*/{"count(a)"},
+ /*keys=*/{"b"}};
+
+ ARROW_ASSIGN_OR_RAISE(cp::ExecNode * aggregate,
+ cp::MakeExecNode("aggregate", plan.get(), {source},
+ aggregate_options));
+
+Aggregate example;
+
+Filter Example;
+
+.. literalinclude::
../../../cpp/examples/arrow/execution_plan_documentation_examples.cc
+ :language: cpp
+ :start-after: (Doc section: Aggregate Example)
+ :end-before: (Doc section: Aggregate Example)
+ :linenos:
+ :lineno-match:
+
+.. _stream_execution_sink_docs:
+
+``sink``
+--------
+
+``sink`` operation can be considered as the option providing output or final
node of an streaming
+execution definition. :class:`arrow::compute::SinkNodeOptions` interface is
used to pass
+the required options. Requires
+``arrow::AsyncGenerator<arrow::util::optional<cp::ExecBatch>>* generator``
+and ``arrow::util::BackpressureOptions backpressure``.
+An execution plan should only have one "terminal" node (one sink node).
Review comment:
Sure, I updated the section.
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