# Aggregate events over a large period of time maintaining previous task maps **URL:** \ **Category:** Logstash\ **Created:** [October 6, 2020, 6:54pm UTC](https://discuss.elastic.co/t/aggregate-events-over-a-large-period-of-time-maintaining-previous-task-maps/251178 "2020-10-06T18:54:00Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![arichiardi](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/arichiardi/32/76109_2.png) [@arichiardi](https://discuss.elastic.co/u/arichiardi)\ **Post date:** [October 6, 2020, 6:54pm UTC](https://discuss.elastic.co/t/aggregate-events-over-a-large-period-of-time-maintaining-previous-task-maps/251178/1 "2020-10-06T18:54:00Z")
Hi all, I am new to logstash and aggregate - but not too event sourcing/CQRS and I am looking for a strategy to handle the following problem. I have a `product.created` that contains the initial available products. I then have consecutive `stock.updated` that contain increments/decrements of the quantity. I am using the aggregate plugin but I am struggling to see how this would work in case the `product created` product comes way before the updates. From what I see every time aggregate times out it evicts the map and this is a problem for me cause when I receive an update I am always going to need the previous result (kind of like doing a reduce over the events). I was wondering if there is a way _not_ to evict the map? Am I doing it right? Thank you in advance for all your answers. ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [November 3, 2020, 6:54pm UTC](https://discuss.elastic.co/t/aggregate-events-over-a-large-period-of-time-maintaining-previous-task-maps/251178/2 "2020-11-03T18:54:01Z")
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