From 186d0f98eebc76708f6e11699bea89dd560fd16f Mon Sep 17 00:00:00 2001
From: Steffen Beyer <steffen@beyer.io>
Date: Mon, 16 Mar 2026 16:22:16 +0100
Subject: [PATCH] improve: NIF-77 single-filter fast path

---
 .../storage/adapters/postgres/events.ex       | 235 ++++++++++--------
 1 file changed, 138 insertions(+), 97 deletions(-)

diff --git a/lib/parrhesia/storage/adapters/postgres/events.ex b/lib/parrhesia/storage/adapters/postgres/events.ex
index ce4a158..e202202 100644
--- a/lib/parrhesia/storage/adapters/postgres/events.ex
+++ b/lib/parrhesia/storage/adapters/postgres/events.ex
@@ -98,22 +98,7 @@ defmodule Parrhesia.Storage.Adapters.Postgres.Events do
   def query_event_refs(_context, filters, opts) when is_list(opts) do
     with :ok <- Filter.validate_filters(filters) do
       now = Keyword.get(opts, :now, System.system_time(:second))
-
-      refs =
-        filters
-        |> event_ref_union_query_for_filters(now, opts)
-        |> subquery()
-        |> then(fn union_query ->
-          from(ref in union_query,
-            group_by: [ref.created_at, ref.id],
-            order_by: [asc: ref.created_at, asc: ref.id],
-            select: %{created_at: ref.created_at, id: ref.id}
-          )
-        end)
-        |> maybe_limit_query(Keyword.get(opts, :limit))
-        |> Repo.all()
-
-      {:ok, refs}
+      {:ok, fetch_event_refs(filters, now, opts)}
     end
   end
 
@@ -123,17 +108,7 @@ defmodule Parrhesia.Storage.Adapters.Postgres.Events do
   def count(_context, filters, opts) when is_list(opts) do
     with :ok <- Filter.validate_filters(filters) do
       now = Keyword.get(opts, :now, System.system_time(:second))
-
-      total_count =
-        filters
-        |> event_id_union_query_for_filters(now, opts)
-        |> subquery()
-        |> then(fn union_query ->
-          from(event in union_query, select: count(event.id, :distinct))
-        end)
-        |> Repo.one()
-
-      {:ok, total_count}
+      {:ok, count_events(filters, now, opts)}
     end
   end
 
@@ -632,81 +607,55 @@ defmodule Parrhesia.Storage.Adapters.Postgres.Events do
   end
 
   defp event_query_for_filter(filter, now, opts) do
-    base_query =
-      from(event in "events",
-        where: is_nil(event.deleted_at) and (is_nil(event.expires_at) or event.expires_at > ^now),
-        order_by: [desc: event.created_at, asc: event.id],
-        select: %{
-          id: event.id,
-          pubkey: event.pubkey,
-          created_at: event.created_at,
-          kind: event.kind,
-          tags: event.tags,
-          content: event.content,
-          sig: event.sig
-        }
-      )
+    {base_query, remaining_tag_filters} = event_source_query(filter, now)
 
-    query =
-      base_query
-      |> maybe_filter_ids(Map.get(filter, "ids"))
-      |> maybe_filter_authors(Map.get(filter, "authors"))
-      |> maybe_filter_kinds(Map.get(filter, "kinds"))
-      |> maybe_filter_since(Map.get(filter, "since"))
-      |> maybe_filter_until(Map.get(filter, "until"))
-      |> maybe_filter_search(Map.get(filter, "search"))
-      |> filter_by_tags(filter)
-      |> maybe_restrict_giftwrap_access(filter, opts)
-
-    maybe_limit_query(query, effective_filter_limit(filter, opts))
+    base_query
+    |> apply_common_event_filters(filter, remaining_tag_filters, opts)
+    |> order_by([event: event], desc: event.created_at, asc: event.id)
+    |> select([event: event], %{
+      id: event.id,
+      pubkey: event.pubkey,
+      created_at: event.created_at,
+      kind: event.kind,
+      tags: event.tags,
+      content: event.content,
+      sig: event.sig
+    })
+    |> maybe_limit_query(effective_filter_limit(filter, opts))
   end
 
   defp event_id_query_for_filter(filter, now, opts) do
-    from(event in "events",
-      where: is_nil(event.deleted_at) and (is_nil(event.expires_at) or event.expires_at > ^now),
-      select: event.id
-    )
-    |> maybe_filter_ids(Map.get(filter, "ids"))
-    |> maybe_filter_authors(Map.get(filter, "authors"))
-    |> maybe_filter_kinds(Map.get(filter, "kinds"))
-    |> maybe_filter_since(Map.get(filter, "since"))
-    |> maybe_filter_until(Map.get(filter, "until"))
-    |> maybe_filter_search(Map.get(filter, "search"))
-    |> filter_by_tags(filter)
-    |> maybe_restrict_giftwrap_access(filter, opts)
+    {base_query, remaining_tag_filters} = event_source_query(filter, now)
+
+    base_query
+    |> apply_common_event_filters(filter, remaining_tag_filters, opts)
+    |> select([event: event], event.id)
   end
 
-  defp event_id_union_query_for_filters([], now, _opts) do
+  defp event_id_distinct_union_query_for_filters([], now, _opts) do
     from(event in "events",
       where: event.created_at > ^now and event.created_at < ^now,
       select: event.id
     )
   end
 
-  defp event_id_union_query_for_filters([first_filter | rest_filters], now, opts) do
+  defp event_id_distinct_union_query_for_filters([first_filter | rest_filters], now, opts) do
     Enum.reduce(rest_filters, event_id_query_for_filter(first_filter, now, opts), fn filter,
                                                                                      acc ->
-      union_all(acc, ^event_id_query_for_filter(filter, now, opts))
+      union(acc, ^event_id_query_for_filter(filter, now, opts))
     end)
   end
 
   defp event_ref_query_for_filter(filter, now, opts) do
-    from(event in "events",
-      where: is_nil(event.deleted_at) and (is_nil(event.expires_at) or event.expires_at > ^now),
-      order_by: [asc: event.created_at, asc: event.id],
-      select: %{
-        created_at: event.created_at,
-        id: event.id
-      }
-    )
-    |> maybe_filter_ids(Map.get(filter, "ids"))
-    |> maybe_filter_authors(Map.get(filter, "authors"))
-    |> maybe_filter_kinds(Map.get(filter, "kinds"))
-    |> maybe_filter_since(Map.get(filter, "since"))
-    |> maybe_filter_until(Map.get(filter, "until"))
-    |> maybe_filter_search(Map.get(filter, "search"))
-    |> filter_by_tags(filter)
-    |> maybe_restrict_giftwrap_access(filter, opts)
+    {base_query, remaining_tag_filters} = event_source_query(filter, now)
+
+    base_query
+    |> apply_common_event_filters(filter, remaining_tag_filters, opts)
+    |> order_by([event: event], asc: event.created_at, asc: event.id)
+    |> select([event: event], %{
+      created_at: event.created_at,
+      id: event.id
+    })
     |> maybe_limit_query(effective_filter_limit(filter, opts))
   end
 
@@ -724,34 +673,128 @@ defmodule Parrhesia.Storage.Adapters.Postgres.Events do
     end)
   end
 
+  defp fetch_event_refs([filter], now, opts) do
+    filter
+    |> event_ref_query_for_filter(now, opts)
+    |> maybe_limit_query(Keyword.get(opts, :limit))
+    |> Repo.all()
+  end
+
+  defp fetch_event_refs(filters, now, opts) do
+    filters
+    |> event_ref_union_query_for_filters(now, opts)
+    |> subquery()
+    |> then(fn union_query ->
+      from(ref in union_query,
+        group_by: [ref.created_at, ref.id],
+        order_by: [asc: ref.created_at, asc: ref.id],
+        select: %{created_at: ref.created_at, id: ref.id}
+      )
+    end)
+    |> maybe_limit_query(Keyword.get(opts, :limit))
+    |> Repo.all()
+  end
+
+  defp count_events([filter], now, opts) do
+    filter
+    |> event_id_query_for_filter(now, opts)
+    |> subquery()
+    |> then(fn query ->
+      from(event in query, select: count())
+    end)
+    |> Repo.one()
+  end
+
+  defp count_events(filters, now, opts) do
+    filters
+    |> event_id_distinct_union_query_for_filters(now, opts)
+    |> subquery()
+    |> then(fn union_query ->
+      from(event in union_query, select: count())
+    end)
+    |> Repo.one()
+  end
+
+  defp event_source_query(filter, now) do
+    tag_filters = tag_filters(filter)
+
+    case primary_tag_filter(tag_filters) do
+      nil ->
+        {from(event in "events",
+           as: :event,
+           where:
+             is_nil(event.deleted_at) and
+               (is_nil(event.expires_at) or event.expires_at > ^now)
+         ), []}
+
+      {tag_name, values} = primary_tag_filter ->
+        remaining_tag_filters = List.delete(tag_filters, primary_tag_filter)
+
+        {from(tag in "event_tags",
+           as: :primary_tag,
+           where: tag.name == ^tag_name and tag.value in ^values,
+           join: event in "events",
+           as: :event,
+           on: event.created_at == tag.event_created_at and event.id == tag.event_id,
+           where:
+             is_nil(event.deleted_at) and
+               (is_nil(event.expires_at) or event.expires_at > ^now),
+           distinct: [event.created_at, event.id]
+         ), remaining_tag_filters}
+    end
+  end
+
+  defp apply_common_event_filters(query, filter, remaining_tag_filters, opts) do
+    query
+    |> maybe_filter_ids(Map.get(filter, "ids"))
+    |> maybe_filter_authors(Map.get(filter, "authors"))
+    |> maybe_filter_kinds(Map.get(filter, "kinds"))
+    |> maybe_filter_since(Map.get(filter, "since"))
+    |> maybe_filter_until(Map.get(filter, "until"))
+    |> maybe_filter_search(Map.get(filter, "search"))
+    |> filter_by_tag_filters(remaining_tag_filters)
+    |> maybe_restrict_giftwrap_access(filter, opts)
+  end
+
+  defp primary_tag_filter([]), do: nil
+
+  defp primary_tag_filter(tag_filters) do
+    Enum.find(tag_filters, fn {tag_name, _values} -> tag_name in ["h", "i"] end) ||
+      List.first(tag_filters)
+  end
+
   defp maybe_filter_ids(query, nil), do: query
 
   defp maybe_filter_ids(query, ids) do
     decoded_ids = decode_hex_list(ids, :lower)
-    where(query, [event], event.id in ^decoded_ids)
+    where(query, [event: event], event.id in ^decoded_ids)
   end
 
   defp maybe_filter_authors(query, nil), do: query
 
   defp maybe_filter_authors(query, authors) do
     decoded_authors = decode_hex_list(authors, :lower)
-    where(query, [event], event.pubkey in ^decoded_authors)
+    where(query, [event: event], event.pubkey in ^decoded_authors)
   end
 
   defp maybe_filter_kinds(query, nil), do: query
-  defp maybe_filter_kinds(query, kinds), do: where(query, [event], event.kind in ^kinds)
+  defp maybe_filter_kinds(query, kinds), do: where(query, [event: event], event.kind in ^kinds)
 
   defp maybe_filter_since(query, nil), do: query
-  defp maybe_filter_since(query, since), do: where(query, [event], event.created_at >= ^since)
+
+  defp maybe_filter_since(query, since),
+    do: where(query, [event: event], event.created_at >= ^since)
 
   defp maybe_filter_until(query, nil), do: query
-  defp maybe_filter_until(query, until), do: where(query, [event], event.created_at <= ^until)
+
+  defp maybe_filter_until(query, until),
+    do: where(query, [event: event], event.created_at <= ^until)
 
   defp maybe_filter_search(query, nil), do: query
 
   defp maybe_filter_search(query, search) when is_binary(search) and search != "" do
     escaped_search = escape_like_pattern(search)
-    where(query, [event], ilike(event.content, ^"%#{escaped_search}%"))
+    where(query, [event: event], ilike(event.content, ^"%#{escaped_search}%"))
   end
 
   defp maybe_filter_search(query, _search), do: query
@@ -763,13 +806,11 @@ defmodule Parrhesia.Storage.Adapters.Postgres.Events do
     |> String.replace("_", "\\_")
   end
 
-  defp filter_by_tags(query, filter) do
-    filter
-    |> tag_filters()
-    |> Enum.reduce(query, fn {tag_name, values}, acc ->
+  defp filter_by_tag_filters(query, tag_filters) do
+    Enum.reduce(tag_filters, query, fn {tag_name, values}, acc ->
       where(
         acc,
-        [event],
+        [event: event],
         fragment(
           "EXISTS (SELECT 1 FROM event_tags AS tag WHERE tag.event_created_at = ? AND tag.event_id = ? AND tag.name = ? AND tag.value = ANY(?))",
           event.created_at,
@@ -799,7 +840,7 @@ defmodule Parrhesia.Storage.Adapters.Postgres.Events do
       targets_giftwrap?(filter) and requester_pubkeys != [] ->
         where(
           query,
-          [event],
+          [event: event],
           fragment(
             "EXISTS (SELECT 1 FROM event_tags AS tag WHERE tag.event_created_at = ? AND tag.event_id = ? AND tag.name = 'p' AND tag.value = ANY(?))",
             event.created_at,
@@ -809,7 +850,7 @@ defmodule Parrhesia.Storage.Adapters.Postgres.Events do
         )
 
       targets_giftwrap?(filter) ->
-        where(query, [_event], false)
+        where(query, [event: _event], false)
 
       true ->
         query