1 files changed, 73 insertions, 0 deletions
diff --git a/db/post_migrate/20230328111013_re_migrate_redis_slot_keys.rb b/db/post_migrate/20230328111013_re_migrate_redis_slot_keys.rb
new file mode 100644
index 00000000000..0d4b31ecc99
--- /dev/null
+++ b/db/post_migrate/20230328111013_re_migrate_redis_slot_keys.rb
@@ -0,0 +1,73 @@
+# frozen_string_literal: true
+
+class ReMigrateRedisSlotKeys < Gitlab::Database::Migration[2.1]
+  disable_ddl_transaction!
+
+  def up
+    Gitlab::UsageDataCounters::HLLRedisCounter.known_events.each do |event|
+      if event[:aggregation].to_sym == :daily
+        migrate_daily_aggregated(event)
+      else
+        migrate_weekly_aggregated(event)
+      end
+    end
+  end
+
+  def down
+    # no-op
+  end
+
+  private
+
+  def migrate_daily_aggregated(event)
+    days_back = Gitlab::UsageDataCounters::HLLRedisCounter::DEFAULT_DAILY_KEY_EXPIRY_LENGTH
+    start_date = Date.today - days_back - 1.day
+    end_date = Date.today + 1.day
+
+    (start_date..end_date).each do |date|
+      rename_key(event, date)
+    end
+  end
+
+  def migrate_weekly_aggregated(event)
+    weeks_back = Gitlab::UsageDataCounters::HLLRedisCounter::DEFAULT_WEEKLY_KEY_EXPIRY_LENGTH
+    start_date = (Date.today - weeks_back).beginning_of_week - 1.day
+    end_date = Date.today.end_of_week + 1.day
+
+    (start_date..end_date).step(7).each { |date| rename_key(event, date) }
+  end
+
+  def rename_key(event, date)
+    old_key = old_redis_key(event, date)
+    new_key = Gitlab::UsageDataCounters::HLLRedisCounter.send(:redis_key, event, date)
+
+    # cannot simply rename due to different slots
+    Gitlab::Redis::SharedState.with do |redis|
+      hll_blob = redis.get(old_key)
+
+      break unless hll_blob
+
+      temp_key = new_key + "_#{Time.current.to_i}"
+      ttl = redis.ttl(old_key)
+      ttl = ttl > 0 ? ttl : Gitlab::UsageDataCounters::HLLRedisCounter.send(:expiry, event)
+
+      redis.multi do |multi|
+        multi.set(temp_key, hll_blob, ex: 1.day.to_i)
+        multi.pfmerge(new_key, new_key, temp_key)
+        multi.expire(new_key, ttl)
+      end
+
+      redis.del(temp_key)
+    end
+  end
+
+  def old_redis_key(event, time)
+    name_with_slot = if event[:redis_slot].present?
+                       event[:name].to_s.gsub(event[:redis_slot], "{#{event[:redis_slot]}}")
+                     else
+                       "{#{event[:name]}}"
+                     end
+
+    Gitlab::UsageDataCounters::HLLRedisCounter.send(:apply_time_aggregation, name_with_slot, time, event)
+  end
+end