From 9a0a7e62a76640c4591e057d224f414229398d1e Mon Sep 17 00:00:00 2001
From: Uku Taht <uku.taht@gmail.com>
Date: Sat, 7 Mar 2026 17:59:47 +0200
Subject: [PATCH 1/2] [perf] skip reading engagements when not necessary

---
 lib/plausible/stats/sql/where_builder.ex | 38 ++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/lib/plausible/stats/sql/where_builder.ex b/lib/plausible/stats/sql/where_builder.ex
index 18a15546c0b1..ee9c4835bfce 100644
--- a/lib/plausible/stats/sql/where_builder.ex
+++ b/lib/plausible/stats/sql/where_builder.ex
@@ -19,6 +19,23 @@ defmodule Plausible.Stats.SQL.WhereBuilder do
   ]
 
   @doc "Builds WHERE clause for a given Query against sessions or events table"
+  def build(:events, query) do
+    base_condition = filter_site_time_range(:events, query)
+
+    engagement_condition =
+      if skip_engagement_events?(query) do
+        dynamic([e], e.name != "engagement")
+      else
+        true
+      end
+
+    query.filters
+    |> Enum.map(&add_filter(:events, query, &1))
+    |> Enum.reduce(dynamic([], ^base_condition and ^engagement_condition), fn condition, acc ->
+      dynamic([], ^acc and ^condition)
+    end)
+  end
+
   def build(table, query) do
     base_condition = filter_site_time_range(table, query)
 
@@ -27,6 +44,27 @@ defmodule Plausible.Stats.SQL.WhereBuilder do
     |> Enum.reduce(base_condition, fn condition, acc -> dynamic([], ^acc and ^condition) end)
   end
 
+  # Engagement events exist solely for time_on_page and scroll_depth tracking.
+  # Because 'name' is part of the events_v2 primary key, adding WHERE name != 'engagement'
+  # lets ClickHouse skip entire index granules with only engagement rows.
+  # This is safe whenever none of the requested metrics or goal filters need engagement rows.
+  defp skip_engagement_events?(query) do
+    :time_on_page not in query.metrics and
+      :scroll_depth not in query.metrics and
+      not scroll_goal_involved?(query)
+  end
+
+  defp scroll_goal_involved?(%{preloaded_goals: %{matching_toplevel_filters: goals}} = query) do
+    Enum.any?(goals, fn goal -> Plausible.Goal.type(goal) == :scroll end) and
+      (Enum.any?(query.filters, fn
+         [_, "event:goal", _] -> true
+         _ -> false
+       end) or
+         "event:goal" in query.dimensions)
+  end
+
+  defp scroll_goal_involved?(_query), do: false
+
   @doc """
   Builds WHERE clause condition based off of a filter and a custom column name
   Used for special business logic cases

From a49b51d20c861d3761f3f89f4f5df24c11d7f8b3 Mon Sep 17 00:00:00 2001
From: Uku Taht <uku.taht@gmail.com>
Date: Sat, 7 Mar 2026 19:29:07 +0200
Subject: [PATCH 2/2] Fix funnel query

---
 extra/lib/plausible/stats/funnel.ex      |  4 ++++
 lib/plausible/stats/sql/where_builder.ex | 10 +++-------
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/extra/lib/plausible/stats/funnel.ex b/extra/lib/plausible/stats/funnel.ex
index a9fae4ca90d6..46ee57b1676d 100644
--- a/extra/lib/plausible/stats/funnel.ex
+++ b/extra/lib/plausible/stats/funnel.ex
@@ -28,6 +28,10 @@ defmodule Plausible.Stats.Funnel do
   end
 
   def funnel(_site, query, %Funnel{} = funnel) do
+    funnel_goals = Enum.map(funnel.steps, & &1.goal)
+
+    query = %{query | preloaded_goals: %{all: funnel_goals}}
+
     funnel_data =
       query
       |> Base.base_event_query()
diff --git a/lib/plausible/stats/sql/where_builder.ex b/lib/plausible/stats/sql/where_builder.ex
index ee9c4835bfce..9cf057c1d49a 100644
--- a/lib/plausible/stats/sql/where_builder.ex
+++ b/lib/plausible/stats/sql/where_builder.ex
@@ -54,13 +54,9 @@ defmodule Plausible.Stats.SQL.WhereBuilder do
       not scroll_goal_involved?(query)
   end
 
-  defp scroll_goal_involved?(%{preloaded_goals: %{matching_toplevel_filters: goals}} = query) do
-    Enum.any?(goals, fn goal -> Plausible.Goal.type(goal) == :scroll end) and
-      (Enum.any?(query.filters, fn
-         [_, "event:goal", _] -> true
-         _ -> false
-       end) or
-         "event:goal" in query.dimensions)
+  defp scroll_goal_involved?(%{preloaded_goals: %{all: goals}} = query) do
+    Enum.any?(goals, fn goal -> Plausible.Goal.type(goal) == :scroll end) or
+      "event:goal" in query.dimensions
   end
 
   defp scroll_goal_involved?(_query), do: false