Make event query faster by eliminating the subquery check for every row.

lib/sequent/core/event_store.rb

@@ -70,16 +70,8 @@ def load_events_for_aggregates(aggregate_ids)
 
         streams = stream_record_class.where(aggregate_id: aggregate_ids)
 
-        events = event_record_class.connection.select_all(%Q{
-SELECT event_type, event_json
-  FROM #{quote_table_name event_record_class.table_name} AS o
-WHERE aggregate_id in (#{aggregate_ids.map{ |aggregate_id| quote(aggregate_id)}.join(",")})
-AND sequence_number >= COALESCE((SELECT MAX(sequence_number)
-                                 FROM #{quote_table_name event_record_class.table_name} AS i
-                                 WHERE event_type = #{quote snapshot_event_class.name}
-                                   AND i.aggregate_id = o.aggregate_id), 0)
-ORDER BY sequence_number ASC, (CASE event_type WHEN #{quote snapshot_event_class.name} THEN 0 ELSE 1 END) ASC
-}).map! do |event_hash|
+        query = aggregate_ids.uniq.map { |aggregate_id| aggregate_query(aggregate_id) }.join(" UNION ALL ")
+        events = event_record_class.connection.select_all(query).map! do |event_hash|
           deserialize_event(event_hash)
         end
 
@@ -88,6 +80,19 @@ def load_events_for_aggregates(aggregate_ids)
           .map { |aggregate_id, _events| [streams.find { |stream_record| stream_record.aggregate_id == aggregate_id }.event_stream, _events] }
       end
 
+      def aggregate_query(aggregate_id)
+        %Q{(
+SELECT event_type, event_json
+  FROM #{quote_table_name event_record_class.table_name} AS o
+WHERE aggregate_id = #{quote(aggregate_id)}
+AND sequence_number >= COALESCE((SELECT MAX(sequence_number)
+                                 FROM #{quote_table_name event_record_class.table_name} AS i
+                                 WHERE event_type = #{quote snapshot_event_class.name}
+                                   AND i.aggregate_id = #{quote(aggregate_id)}), 0)
+ORDER BY sequence_number ASC, (CASE event_type WHEN #{quote snapshot_event_class.name} THEN 0 ELSE 1 END) ASC
+)}
+      end
+
       def stream_exists?(aggregate_id)
         stream_record_class.exists?(aggregate_id: aggregate_id)
       end