As Memcache is not persistent long-term storage, keys are not expected to 
live long and can be evicted for reason explained in our documentation 
<https://cloud.google.com/appengine/docs/python/memcache/#how_cached_data_expires>.
 
As noted 
<https://cloud.google.com/appengine/docs/python/memcache/#service_levels>, 
even Dedicated Memcache follows the LRU eviction policy. This means that 
pushing the limit of your set dedicated Memcache size will begin to evict 
the oldest keys. You can increase the size of your dedicated Memcache by 
clicking the 'Change' button in your Console 
<https://console.cloud.google.com/appengine/memcache> to alleviated this 
pressure.

Specifically with Dedicated Memcache, it is your app's behavior that will 
evict its own keys. If you write to the same objects or keys, you will in 
turn evict the previous item you are overwriting to make room for the new 
change. The same is also true for deleting keys, as they will also be 
evicted. Apps that overload their task(s) will end up hurting itself as 
well. I highly recommend you abide by the Ops/Sec/GB limit shown in your 
Console <https://console.cloud.google.com/appengine/memcache> for your set 
Memcache size as explained in our documentation 
<https://cloud.google.com/appengine/docs/python/memcache/#operations_per_second_by_item_size>.
 
This will ensure that you are optimizing your interactions and operations 
to make the most out of the space you are allotted. 

If after performing the above recommendations, you are still seeing this 
set eviction date of 2 days, I ask that you provide more information about 
your usage of Memcahce, and your business need to have items stored for 365 
days. Providing code samples of your interactions will also help in my 
investigations. 

On Friday, October 7, 2016 at 11:30:44 PM UTC-4, Vinay Chitlangia wrote:
>
> We are using dedicated memcache in our application. Curiously the oldest 
> cached key time is almost always 1-2 days.
> The dedicated quota is 1GB and the cache size never crosses 500MB.
>
> Entries are made to memcache with 365 days expiration time.
>
> Wondering if this is expected that the cache will keep purging data on a 
> 1-2 day scale.
>

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  • [google-appengine]... Vinay Chitlangia
    • [google-appen... 'Jordan (Cloud Platform Support)' via Google App Engine

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