#434

backend/app/services/counts_condition.rb

@@ -340,7 +340,7 @@ class CountsCondition
       return @definition.alias_source(root) if root.start_with?('aliases_')
       return [nil, @definition.name_expression(root)]
     end
-    return [nil, "(#{ @population.latest_sql })"] if root == 'latest'
+    return [nil, "(#{ @population.current_latest_sql })"] if root == 'latest'
     if root == 'user' && parts.any?
       expression = parts.first == 'id' ? 'v.created_by_user_id' :
           '(SELECT actor.name FROM users actor WHERE actor.id = v.created_by_user_id)'

backend/app/services/counts_defaults.rb

@@ -20,7 +20,7 @@ class CountsDefaults
       details = details.transform_values do |value|
         value.split(' ').flat_map do |token|
           if resource == 'tags' && ['name', 'parents.name'].include?(token)
-            token == 'name' ? name : ["parents.#{ name }", "parents.#{ aliases }"]
+            token == 'name' ? name : "parents.#{ name }"
           elsif resource == 'tags' && token == 'aliases'
             aliases
           elsif resource == 'tags' && token.start_with?('aliases.')

backend/app/services/counts_population.rb

@@ -41,8 +41,7 @@ class CountsPopulation
     raise ArgumentError
   end
 
-  def latest_sql(row = 'v', cutoff = nil)
-    cutoff ||= history ? at : timestamp(params['at']) || at
+  def latest_at_sql(row, cutoff)
     keys = definition.keys.map { "newer.#{ _1 } = #{ row }.#{ _1 }" }.join(' AND ')
     bound = definition.model.connection.quote(cutoff)
     <<~SQL.squish
@@ -52,6 +51,14 @@ class CountsPopulation
     SQL
   end
 
+  def current_latest_sql(row = 'v')
+    keys = definition.keys.map { "newer.#{ _1 } = #{ row }.#{ _1 }" }.join(' AND ')
+    <<~SQL.squish
+      NOT EXISTS (SELECT 1 FROM #{ definition.table } newer
+        WHERE #{ keys } AND newer.version_no > #{ row }.version_no)
+    SQL
+  end
+
   def changed_sql(key)
     column = definition.column(key)
     "(previous.id IS NOT NULL AND NOT (v.#{ column } <=> previous.#{ column }))"
@@ -125,7 +132,7 @@ class CountsPopulation
       raise ArgumentError if point > at
 
       @scope = @scope.where("v.#{ definition.time_column } <= ?", point)
-          .where(Arel.sql(latest_sql('v', point))).where.not('v.event_type' => 'discard')
+          .where(Arel.sql(latest_at_sql('v', point))).where.not('v.event_type' => 'discard')
       return
     end
     first = timestamp(params['from'])

backend/app/services/counts_table_query.rb

@@ -1,5 +1,7 @@
 # Common entrypoint for six version resources; legacy endpoints keep their contracts.
 class CountsTableQuery
+  SQL_HINTS = ['MAX_EXECUTION_TIME(10000)',
+               "SET_VAR(optimizer_switch='semijoin=off')"].freeze
   MAX_COLUMNS = 100
   class TooManyColumns < ArgumentError; end
 
@@ -127,7 +129,7 @@ class CountsTableQuery
       numbered AS (SELECT row_groups.*,
         ROW_NUMBER() OVER (ORDER BY #{ order_rows.join(', ') }) AS position FROM row_groups),
       group_totals AS (SELECT COUNT(*) AS group_count FROM row_groups)
-      SELECT /*+ MAX_EXECUTION_TIME(10000) */ cells.*,
+      SELECT /*+ #{ SQL_HINTS.join(' ') } */ cells.*,
         page_rows.position AS counts_position, group_totals.group_count AS counts_group_count
       FROM group_totals LEFT JOIN numbered page_rows
         ON page_rows.position > #{ (page - 1) * limit }
@@ -175,7 +177,7 @@ class CountsTableQuery
 
   def details
     query = population.scope.select(Arel.sql(
-        "(#{ population.latest_sql }) AS counts_latest"))
+        "(#{ population.current_latest_sql }) AS counts_latest"))
     order = sort_sql { detail_expression(_1) }
     query = query.order(Arel.sql((order + ['v.id ASC']).join(', ')))
         .limit(limit).offset((page - 1) * limit)
@@ -253,11 +255,11 @@ class CountsTableQuery
 
     if HistoryAccess.admin? || mode == 'summary'
       total = population.scope.except(:select)
-          .optimizer_hints('MAX_EXECUTION_TIME(10000)').count
+          .optimizer_hints(*SQL_HINTS).count
       return @record_counts = { total:, visible: total, denied: 0 }
     end
     total, denied = unrestricted_population.scope.except(:select)
-        .optimizer_hints('MAX_EXECUTION_TIME(10000)').pick(Arel.sql('COUNT(*)'),
+        .optimizer_hints(*SQL_HINTS).pick(Arel.sql('COUNT(*)'),
             Arel.sql("COALESCE(SUM(CASE WHEN #{ HistoryAccess.sql(@definition.model, 'v') } " +
                 'THEN 0 ELSE 1 END), 0)'))
     # Related/previous-version predicates may differ under public authority.
@@ -267,7 +269,7 @@ class CountsTableQuery
                 total.to_i - denied.to_i
               else
                 population.scope.except(:select)
-                    .optimizer_hints('MAX_EXECUTION_TIME(10000)').count
+                    .optimizer_hints(*SQL_HINTS).count
               end
     @record_counts = { total: total.to_i, denied: denied.to_i, visible: }
   end
@@ -309,7 +311,7 @@ class CountsTableQuery
     prefix = "WITH cells AS (#{ sql })"
     @connection.select_value(<<~SQL).to_i
       #{ prefix }
-      SELECT /*+ MAX_EXECUTION_TIME(10000) */ COUNT(*) FROM (
+      SELECT /*+ #{ SQL_HINTS.join(' ') } */ COUNT(*) FROM (
         SELECT #{ keys.join(', ') } FROM cells GROUP BY #{ keys.join(', ') }
       ) output_groups
     SQL
@@ -335,7 +337,7 @@ class CountsTableQuery
     end
     values = @connection.select_rows(<<~SQL)
       #{ prefix }
-      SELECT /*+ MAX_EXECUTION_TIME(10000) */ DISTINCT #{ keys.join(', ') } FROM cells
+      SELECT /*+ #{ SQL_HINTS.join(' ') } */ DISTINCT #{ keys.join(', ') } FROM cells
       ORDER BY #{ order } LIMIT #{ MAX_COLUMNS + 1 }
     SQL
     raise TooManyColumns if values.length > MAX_COLUMNS
@@ -395,7 +397,7 @@ class CountsTableQuery
   end
 
   def detail_expression(key)
-    return "(#{ population.latest_sql })" if key == 'latest'
+    return "(#{ population.current_latest_sql })" if key == 'latest'
     return @definition.name_expression(key) if @definition.resource == 'tags' &&
         @definition.name_column(key)
     aliases = { 'tags' => 'tags_json', 'parents' => @definition.resource == 'posts' ?