Purge legacy is_grid_point=true rows from hrrr_profiles

The grid worker stopped writing HRRR profiles to the DB on April 14
when the forecast grid moved to /data/scores binary files, but the
24/72h-windowed prune left every is_grid_point=true row older than
72 hours sitting in the table (billions of rows across every
partition back to 2016, ~90% of the 146 GB table size). Nothing
reads them anymore.

Replace prune_old_grid_profiles/0 with purge_grid_point_profiles/0,
which walks every hrrr_profiles partition directly and deletes
is_grid_point=true rows regardless of age. Per-partition DELETEs
avoid a parent-table full scan. QSO-linked rows (is_grid_point=false)
are untouched — those still back contact enrichment and /path.

Call the new purge from the grid worker's end-of-chain hook so any
grid-point row that somehow slips back in gets cleaned up within the
next hour. Add `mix hrrr.purge_grid_points` for a one-shot historical
cleanup.

lib/microwaveprop/weather.ex

@@ -922,39 +922,56 @@ defmodule Microwaveprop.Weather do
   end
 
   @doc """
-  Delete HRRR grid profiles older than 24 hours that sit on the 0.125° grid.
-  Preserves QSO-linked profiles which are at arbitrary lat/lon positions.
-  With 19 forecast hours per run, this keeps ~2 runs worth of grid profiles.
+  Delete every `is_grid_point = true` row from `hrrr_profiles`, regardless of
+  age. Grid-point profiles are historical — the propagation grid now lives in
+  `/data/scores` binary files, nothing reads `is_grid_point = true` rows
+  anymore, and forecast runs no longer write them. This purge walks each
+  partition directly so a single DELETE can't scan the whole parent table.
+  Preserves QSO-linked rows (`is_grid_point = false`), which remain the data
+  path for contact enrichment and the `/path` calculator.
   """
-  @spec prune_old_grid_profiles() :: non_neg_integer()
-  def prune_old_grid_profiles do
-    cutoff = DateTime.add(DateTime.utc_now(), -24, :hour)
-    # Bound the scan to recent partitions only (grid profiles are at most ~48h old).
-    # Without a lower bound, Postgres scans every partition back to 2016.
-    floor = DateTime.add(DateTime.utc_now(), -72, :hour)
+  @spec purge_grid_point_profiles() :: non_neg_integer()
+  def purge_grid_point_profiles do
+    deleted =
+      Enum.reduce(hrrr_profile_partitions(), 0, fn partition, acc ->
+        %{num_rows: n} =
+          Repo.query!(
+            ~s(DELETE FROM "#{partition}" WHERE is_grid_point = true),
+            [],
+            timeout: 600_000
+          )
 
-    # Only delete profiles on the 0.125° propagation grid, preserving QSO-linked
-    # profiles which sit at arbitrary lat/lon positions (HRRR's native ~3km grid).
-    %{num_rows: deleted} =
-      Repo.query!(
-        """
-        DELETE FROM hrrr_profiles
-        WHERE valid_time >= $2 AND valid_time < $1
-          AND is_grid_point = true
-        """,
-        [cutoff, floor],
-        timeout: 300_000
-      )
+        if n > 0 do
+          require Logger
 
-    if deleted > 0 do
-      require Logger
+          Logger.info("Purged #{n} grid-point rows from #{partition}")
+        end
 
-      Logger.info("Pruned #{deleted} old HRRR grid profiles (valid_time < #{cutoff})")
-    end
+        acc + n
+      end)
 
     deleted
   end
 
+  @spec hrrr_profile_partitions() :: [String.t()]
+  defp hrrr_profile_partitions do
+    {:ok, %{rows: rows}} =
+      Repo.query(
+        """
+        SELECT child.relname
+        FROM pg_inherits
+        JOIN pg_class parent ON pg_inherits.inhparent = parent.oid
+        JOIN pg_class child  ON pg_inherits.inhrelid  = child.oid
+        WHERE parent.relname = 'hrrr_profiles'
+        ORDER BY child.relname
+        """,
+        [],
+        timeout: 60_000
+      )
+
+    Enum.map(rows, fn [name] -> name end)
+  end
+
   @spec round_to_iemre_grid(float(), float()) :: {float(), float()}
   def round_to_iemre_grid(lat, lon) do
     {Float.round(lat * 8) / 8, Float.round(lon * 8) / 8}

lib/microwaveprop/workers/propagation_grid_worker.ex

@@ -133,7 +133,7 @@ defmodule Microwaveprop.Workers.PropagationGridWorker do
   # Split into its own function to keep `run_chain_step/2` under
   # credo's nesting limit.
   defp handle_step_transition(:final, run_time) do
-    Weather.prune_old_grid_profiles()
+    Weather.purge_grid_point_profiles()
     Propagation.prune_old_scores()
     # Drop any files left over from the previous chain that the new
     # chain didn't happen to overwrite (files are keyed by

lib/mix/tasks/hrrr_purge_grid_points.ex

@@ -0,0 +1,28 @@
+defmodule Mix.Tasks.Hrrr.PurgeGridPoints do
+  @shortdoc "Delete every `is_grid_point = true` row from hrrr_profiles"
+
+  @moduledoc """
+  Removes every `is_grid_point = true` row from `hrrr_profiles` across every
+  partition. The propagation grid now lives in `/data/scores` binary files,
+  nothing reads grid-point rows anymore, and the grid worker no longer writes
+  them — this task reclaims the disk space from the legacy data that
+  accumulated before the April 14 cutover.
+
+  Leaves `is_grid_point = false` (QSO-linked) rows untouched.
+
+      mix hrrr.purge_grid_points
+  """
+
+  use Mix.Task
+
+  alias Microwaveprop.Weather
+
+  @impl Mix.Task
+  def run(_argv) do
+    Mix.Task.run("app.start")
+
+    Mix.shell().info("Purging grid-point rows from hrrr_profiles...")
+    deleted = Weather.purge_grid_point_profiles()
+    Mix.shell().info("Purged #{deleted} grid-point rows total.")
+  end
+end

test/microwaveprop/weather_test.exs

@@ -468,6 +468,58 @@ defmodule Microwaveprop.WeatherTest do
     end
   end
 
+  describe "purge_grid_point_profiles/0" do
+    test "deletes all grid-point rows across partitions while preserving QSO-linked rows" do
+      # QSO-linked row (is_grid_point defaults to false)
+      {:ok, qso_linked} = Weather.upsert_hrrr_profile(@hrrr_profile_attrs)
+
+      # Grid-point row in a historical partition
+      Repo.query!(
+        """
+        INSERT INTO hrrr_profiles
+          (id, valid_time, lat, lon, is_grid_point, inserted_at, updated_at)
+        VALUES ($1, $2, $3, $4, true, $5, $5)
+        """,
+        [
+          Ecto.UUID.bingenerate(),
+          ~N[2023-07-15 12:00:00],
+          32.125,
+          -97.125,
+          NaiveDateTime.truncate(NaiveDateTime.utc_now(), :second)
+        ]
+      )
+
+      # Grid-point row in the current partition
+      Repo.query!(
+        """
+        INSERT INTO hrrr_profiles
+          (id, valid_time, lat, lon, is_grid_point, inserted_at, updated_at)
+        VALUES ($1, $2, $3, $4, true, $5, $5)
+        """,
+        [
+          Ecto.UUID.bingenerate(),
+          NaiveDateTime.truncate(NaiveDateTime.utc_now(), :second),
+          33.125,
+          -96.125,
+          NaiveDateTime.truncate(NaiveDateTime.utc_now(), :second)
+        ]
+      )
+
+      assert Repo.aggregate(HrrrProfile, :count) == 3
+      assert Weather.purge_grid_point_profiles() == 2
+
+      remaining = Repo.all(HrrrProfile)
+      assert length(remaining) == 1
+      assert hd(remaining).id == qso_linked.id
+    end
+
+    test "returns 0 when there are no grid-point rows" do
+      {:ok, _} = Weather.upsert_hrrr_profile(@hrrr_profile_attrs)
+      assert Weather.purge_grid_point_profiles() == 0
+      assert Repo.aggregate(HrrrProfile, :count) == 1
+    end
+  end
+
   describe "has_hrrr_profile?/3" do
     test "returns true when a profile exists at the given location and time" do
       Weather.upsert_hrrr_profile(@hrrr_profile_attrs)