Merge branch 'fix/DEX-2876/optimize-min-query' into 'master'

[DEX-2876] Optimize 'MIN(created_at)' query

Closes DEX-2876

See merge request nstmrt/rubygems/outbox!118

Author: Черненков Алексей Юрьевич

CHANGELOG.md

@@ -13,6 +13,12 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Fixed
 
+## [6.19.1] - 2025-02-20
+
+### Fixed
+
+- `MIN(created_at)` query in stale items deletion job has been optimised
+
 ## [6.19.0] - 2025-02-11
 
 ### Added

app/jobs/sbmt/outbox/base_delete_stale_items_job.rb

@@ -118,7 +118,10 @@ def delete_items_in_batches_with_between(waterline, statuses)
         batch_size = item_class.config.deletion_batch_size
         time_window = item_class.config.deletion_time_window
         min_date = Outbox.database_switcher.use_slave do
-          item_class.where(table[:status].in(statuses)).minimum(:created_at)
+          # This query assumes that record with minimum 'id' also has minimum 'created_at'.
+          # We use it because it should be faster than plain 'SELECT MIN(created_at) ...'.
+          min_id = item_class.select(table[:id].minimum).where(status: statuses)
+          item_class.select(:created_at).where(table[:id].eq(min_id.arel)).first&.created_at
         end
         deleted_count = nil
 
@@ -174,10 +177,14 @@ def mysql_delete_in_batches(waterline_failed, waterline_delivered)
       end
 
       def delete_items_in_batches_with_between_mysql(waterline, statuses)
+        table = item_class.arel_table
         batch_size = item_class.config.deletion_batch_size
         time_window = item_class.config.deletion_time_window
         min_date = Outbox.database_switcher.use_slave do
-          item_class.where(status: statuses).minimum(:created_at)
+          # This query assumes that record with minimum 'id' also has minimum 'created_at'.
+          # We use it because plain 'SELECT MIN(created_at) ...' is VERY slow in MySQL.
+          min_id = item_class.select(table[:id].minimum).where(status: statuses)
+          item_class.select(:created_at).where(table[:id].eq(min_id.arel)).first&.created_at
         end
         deleted_count = nil
 

lib/sbmt/outbox/version.rb

@@ -2,6 +2,6 @@
 
 module Sbmt
   module Outbox
-    VERSION = "6.19.0"
+    VERSION = "6.19.1"
   end
 end