From 07ffd70d6deb0f76e788fad78e7875fc25a99b66 Mon Sep 17 00:00:00 2001
From: joocer <justin.joyce@joocer.com>
Date: Tue, 21 Jan 2025 22:33:31 +0000
Subject: [PATCH] #2264

---
 opteryx/operators/filter_node.py | 70 ++++++++------------------------
 1 file changed, 16 insertions(+), 54 deletions(-)

diff --git a/opteryx/operators/filter_node.py b/opteryx/operators/filter_node.py
index e95c6c692..f4fad1a72 100644
--- a/opteryx/operators/filter_node.py
+++ b/opteryx/operators/filter_node.py
@@ -11,13 +11,10 @@
 This node is responsible for applying filters to datasets.
 """
 
-import multiprocessing
-
 import numpy
 import pyarrow
 
 from opteryx import EOS
-from opteryx.config import CONCURRENT_WORKERS
 from opteryx.exceptions import SqlError
 from opteryx.managers.expression import NodeType
 from opteryx.managers.expression import evaluate
@@ -28,32 +25,6 @@
 
 from . import BasePlanNode
 
-multiprocessing.set_start_method("fork", force=True)
-
-
-def _parallel_filter(queue, morsel, function_evaluations, filters):
-    if function_evaluations:
-        morsel = evaluate_and_append(function_evaluations, morsel)
-    mask = evaluate(filters, morsel)
-
-    if not isinstance(mask, pyarrow.lib.BooleanArray):
-        try:
-            mask = pyarrow.array(mask, type=pyarrow.bool_())
-        except Exception as err:  # nosec
-            raise SqlError(f"Unable to filter on expression '{format_expression(filters)} {err}'.")
-
-    mask = numpy.nonzero(mask)[0]
-    # if there's no matching rows, don't return anything
-    if mask.size > 0 and not numpy.all(mask is None):
-        morsel = morsel.take(pyarrow.array(mask))
-    else:
-        morsel = morsel.slice(0, 0)
-
-    if queue is not None:
-        queue.put(morsel)
-    else:
-        return morsel
-
 
 class FilterNode(BasePlanNode):
     def __init__(self, properties: QueryProperties, **parameters):
@@ -82,30 +53,21 @@ def execute(self, morsel: pyarrow.Table, **kwargs) -> pyarrow.Table:
             yield morsel
             return
 
-        if morsel.num_rows <= 10000 or CONCURRENT_WORKERS <= 2:
-            yield _parallel_filter(None, morsel, self.function_evaluations, self.filter)
-        else:
-            workers = []
-            queue = multiprocessing.Queue()
-
-            for block in morsel.to_batches(((morsel.num_rows + 1) // CONCURRENT_WORKERS)):
-                block = pyarrow.Table.from_batches([block])
-                p = multiprocessing.Process(
-                    target=_parallel_filter,
-                    args=(queue, block, self.function_evaluations, self.filter),
-                )
-                p.start()
-                workers.append(p)
-
-            # Collect all results from the queue
-            results = []
-            for _ in workers:  # Expecting one result per worker
-                results.append(queue.get())  # This will block until a result is available
+        if self.function_evaluations:
+            morsel = evaluate_and_append(self.function_evaluations, morsel)
+        mask = evaluate(self.filter, morsel)
 
-            # Merge all results and return them
-            if results:
-                yield pyarrow.concat_tables(results)
+        if not isinstance(mask, pyarrow.lib.BooleanArray):
+            try:
+                mask = pyarrow.array(mask, type=pyarrow.bool_())
+            except Exception as err:  # nosec
+                raise SqlError(
+                    f"Unable to filter on expression '{format_expression(self.filter)} {err}'."
+                )
+        mask = numpy.nonzero(mask)[0]
 
-            # Ensure all workers have finished before exiting
-            for p in workers:
-                p.join()
+        # if there's no matching rows, don't return anything
+        if mask.size > 0 and not numpy.all(mask is None):
+            yield morsel.take(pyarrow.array(mask))
+        else:
+            yield morsel.slice(0, 0)