Bug 1944375 - Improve data cycling for TryDataRemoval

Author: junngo

treeherder/model/data_cycling/removal_strategies.py

@@ -175,14 +175,55 @@ def name(self) -> str:
         return "try data removal strategy"
 
     def __attempt_remove(self, using):
-        deleted, _ = PerformanceDatum.objects.filter(
-            id__in=PerformanceDatum.objects.filter(
-                repository_id=self.try_repo,
-                push_timestamp__lte=self._max_timestamp,
-                signature_id__in=self.target_signatures,
-            ).values_list("id")[: self._chunk_size]
-        ).delete()
-        using.rowcount = deleted
+        """
+        Raw SQL is used to avoid Django ORM cascade deletes on performance_datum_replicate.
+        Some conditions are intentionally repeated to help the DB planner reduce the candidate rows
+        in the del_replicate CTE.
+        """
+        using.execute(
+            """
+            WITH target_datum AS (
+                SELECT pd.id, pd.repository_id, pd.push_timestamp, pd.signature_id
+                FROM performance_datum pd
+                WHERE pd.repository_id = %s
+                AND pd.push_timestamp <= %s
+                AND pd.signature_id = ANY(%s)
+                LIMIT %s
+            ),
+            del_replicate AS (
+                DELETE FROM performance_datum_replicate r1
+                WHERE r1.performance_datum_id IN (
+                    SELECT td.id
+                    FROM target_datum td
+                    WHERE td.repository_id = %s
+                    AND td.push_timestamp <= %s
+                    AND td.signature_id = ANY(%s)
+                    AND EXISTS (
+                        SELECT 1
+                        FROM performance_datum_replicate r2
+                        WHERE r2.performance_datum_id = td.id
+                    )
+                )
+            ),
+            del_multi AS (
+                DELETE FROM perf_multicommitdatum pm
+                USING target_datum td
+                WHERE pm.perf_datum_id = td.id
+            )
+            DELETE FROM performance_datum pd
+            USING target_datum td
+            WHERE pd.id = td.id
+            """,
+            [
+                self.try_repo,
+                self._max_timestamp,
+                list(self.target_signatures),
+                self._chunk_size,
+                self.try_repo,
+                self._max_timestamp,
+                list(self.target_signatures),
+            ],
+        )
 
     def __lookup_new_signature(self):
         self.__target_signatures = self.__try_signatures[: self.SIGNATURE_BULK_SIZE]