diff --git a/oonipipeline/src/oonipipeline/temporal/activities/analysis.py b/oonipipeline/src/oonipipeline/temporal/activities/analysis.py
index 7c39c89c..83af92ad 100644
--- a/oonipipeline/src/oonipipeline/temporal/activities/analysis.py
+++ b/oonipipeline/src/oonipipeline/temporal/activities/analysis.py
@@ -117,6 +117,9 @@ def make_analysis_in_a_day(params: MakeAnalysisParams) -> dict:
     column_names_wa = [f.name for f in dataclasses.fields(WebAnalysis)]
     column_names_er = [f.name for f in dataclasses.fields(MeasurementExperimentResult)]
 
+    # TODO(art): this previous range search and deletion makes the idempotence
+    # of the activity not 100% accurate.
+    # We should look into fixing it.
     prev_range_list = [
         get_prev_range(
             db=db_lookup,
diff --git a/oonipipeline/src/oonipipeline/temporal/activities/observations.py b/oonipipeline/src/oonipipeline/temporal/activities/observations.py
index 279b3776..8ea28288 100644
--- a/oonipipeline/src/oonipipeline/temporal/activities/observations.py
+++ b/oonipipeline/src/oonipipeline/temporal/activities/observations.py
@@ -141,6 +141,9 @@ def make_observations_for_file_entry_batch(
 def make_observation_in_day(params: MakeObservationsParams) -> dict:
     day = datetime.strptime(params.bucket_date, "%Y-%m-%d").date()
 
+    # TODO(art): this previous range search and deletion makes the idempotence
+    # of the activity not 100% accurate.
+    # We should look into fixing it.
     with ClickhouseConnection(params.clickhouse, row_buffer_size=10_000) as db:
         prev_ranges = []
         for table_name in ["obs_web"]: