Perf: canonical PV fn přes plpgsql execute format — vynucený plán dle skutečných hodnot

set plan_cache_mode=force_custom_plan na SQL funkci v PG 18 nezabral (stále
generický plán, 4.5-9 s / 600k buffers). plpgsql EXECUTE s literály = vždy
čerstvý plán: tělo s konstantami změřeno 0.42 s / 34k buffers. Signatura,
chování i výstup beze změny.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

db/routines/R__088_fn_forecast_pv_slots_range_canonical_ab.sql

@@ -25,27 +25,31 @@ create or replace function ems.fn_forecast_pv_slots_range_canonical_ab(
   p_decay_slots int default 16
 )
 returns jsonb
-language sql
+language plpgsql
 stable
 set work_mem = '64MB'
--- PG 18 cachuje plány SQL funkcí → generický plán bez znalosti hodnot parametrů
--- (4.5 s / 607k buffers); s custom planem dle skutečných hodnot 0.4 s / 34k.
-set plan_cache_mode = force_custom_plan
 as $fn$
+declare
+  v_result jsonb;
+begin
+  -- PG 18 cachuje plán SQL/plpgsql statementů s parametry → generický plán
+  -- (4.5–9 s / 600k buffers); force_custom_plan na funkci nepomohl. Execute
+  -- s literály vynutí čerstvý plán dle skutečných hodnot: 0.4 s / 34k buffers.
+  execute format($q$
   with tz as (
     select coalesce(nullif(trim(s.timezone), ''), 'Europe/Prague') as tz_name
     from ems.site s
-    where s.id = p_site_id
+    where s.id = %1$s
   ),
   bounds as (
     select
-      date_bin(interval '15 minutes', p_from, timestamptz '1970-01-01T00:00:00Z') as ts_from,
+      date_bin(interval '15 minutes', %2$L::timestamptz, timestamptz '1970-01-01T00:00:00Z') as ts_from,
       case
-        when p_to <= p_from then date_bin(interval '15 minutes', p_from, timestamptz '1970-01-01T00:00:00Z') + interval '15 minutes'
+        when %3$L::timestamptz <= %2$L::timestamptz then date_bin(interval '15 minutes', %2$L::timestamptz, timestamptz '1970-01-01T00:00:00Z') + interval '15 minutes'
-        when p_to > p_from + interval '60 days' then date_bin(interval '15 minutes', p_from, timestamptz '1970-01-01T00:00:00Z') + interval '60 days'
+        when %3$L::timestamptz > %2$L::timestamptz + interval '60 days' then date_bin(interval '15 minutes', %2$L::timestamptz, timestamptz '1970-01-01T00:00:00Z') + interval '60 days'
-        else date_bin(interval '15 minutes', p_to, timestamptz '1970-01-01T00:00:00Z')
+        else date_bin(interval '15 minutes', %3$L::timestamptz, timestamptz '1970-01-01T00:00:00Z')
       end as ts_to,
-      date_bin(interval '15 minutes', p_now, timestamptz '1970-01-01T00:00:00Z') as now_slot
+      date_bin(interval '15 minutes', %4$L::timestamptz, timestamptz '1970-01-01T00:00:00Z') as now_slot
   ),
   slot_spine as (
     select gs as interval_start
@@ -68,11 +72,11 @@ as $fn$
   ),
   factor_raw as (
     select ems.fn_pv_forecast_correction_factor(
-      p_site_id,
+      %1$s,
-      (p_now - (p_factor_window_h::text || ' hours')::interval)::timestamptz,
+      (%4$L::timestamptz - (%9$s::text || ' hours')::interval)::timestamptz,
-      p_now,
+      %4$L::timestamptz,
-      p_factor_min_clamp,
+      %10$s,
-      p_factor_max_clamp
+      %11$s
     ) as j
   ),
   factor as (
@@ -82,11 +86,11 @@ as $fn$
   ),
   profile as (
     select ems.fn_pv_forecast_delta_profile_cached(
-      p_site_id,
+      %1$s,
-      p_delta_data_from,
+      %5$L::timestamptz,
-      p_delta_data_to,
+      %6$L::timestamptz,
-      p_half_life_days,
+      %7$s,
-      p_threshold_w
+      %8$s
     ) as j
   ),
   delta_by_array as (
@@ -117,16 +121,16 @@ as $fn$
       on fpi.interval_start >= b.ts_from
      and fpi.interval_start < b.ts_to
      and fpi.pv_array_id in (
-       select apa0.id from ems.asset_pv_array apa0 where apa0.site_id = p_site_id
+       select apa0.id from ems.asset_pv_array apa0 where apa0.site_id = %1$s
      )
     inner join ems.forecast_pv_run fpr
       on fpr.id = fpi.run_id
-     and fpr.site_id = p_site_id
+     and fpr.site_id = %1$s
      and fpr.pv_array_id = fpi.pv_array_id
      and fpr.status = 'ok'
     inner join ems.asset_pv_array apa
       on apa.id = fpr.pv_array_id
-     and apa.site_id = p_site_id
+     and apa.site_id = %1$s
     order by fpi.interval_start, fpr.pv_array_id, fpr.created_at desc
   ),
   fc_with_sod as (
@@ -193,11 +197,11 @@ as $fn$
       f.rolling_factor,
       case
         when ab.interval_start < b.now_slot then 1.0::numeric
-        when p_decay_slots <= 0 then f.rolling_factor
+        when %12$s <= 0 then f.rolling_factor
         else
           case
-            when ((extract(epoch from (ab.interval_start - b.now_slot)) / 900)::int) >= p_decay_slots then 1.0::numeric
+            when ((extract(epoch from (ab.interval_start - b.now_slot)) / 900)::int) >= %12$s then 1.0::numeric
-            else (1.0::numeric + (f.rolling_factor - 1.0::numeric) * (1.0::numeric - ((extract(epoch from (ab.interval_start - b.now_slot)) / 900)::numeric / p_decay_slots::numeric)))
+            else (1.0::numeric + (f.rolling_factor - 1.0::numeric) * (1.0::numeric - ((extract(epoch from (ab.interval_start - b.now_slot)) / 900)::numeric / %12$s::numeric)))
           end
       end as rolling_effective_factor
     from fc_ab ab
@@ -225,7 +229,23 @@ as $fn$
     ),
     '[]'::jsonb
   )
-  from with_factor w;
+  from with_factor w
+$q$,
+    p_site_id,
+    p_from,
+    p_to,
+    p_now,
+    p_delta_data_from,
+    p_delta_data_to,
+    p_half_life_days,
+    p_threshold_w,
+    p_factor_window_h,
+    p_factor_min_clamp,
+    p_factor_max_clamp,
+    p_decay_slots
+  ) into v_result;
+  return coalesce(v_result, '[]'::jsonb);
+end;
 $fn$;
 
 comment on function ems.fn_forecast_pv_slots_range_canonical_ab is