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From Denis Magda <dma...@apache.org>
Subject Re: Data eviction/expiration from Ignite persistence
Date Mon, 20 Nov 2017 23:13:28 GMT

That’s about TTL and eviction support for Ignite persistence. Presently if you set an expiration
or eviction policy for a cache it will be applied for data stored in memory. The policy never
affects the persistence layer.


> On Nov 20, 2017, at 9:29 AM, Dmitry Pavlov <dpavlov.spb@gmail.com> wrote:
> Hi Denis,
> Is this need covered by PDS + TTL?
> For the very first TTL test, I found some delay after applying TTL with the
> repository enabled: https://issues.apache.org/jira/browse/IGNITE-6964
> And I'm wondering if the user's needs are covered by
> https://apacheignite.readme.io/docs/expiry-policies plus
> https://apacheignite.readme.io/docs/distributed-persistent-store
> Sincerely,
> Dmitriy Pavlov
> сб, 18 нояб. 2017 г. в 12:12, Dmitry Pavlov <dpavlov.spb@gmail.com>:
>> Hi Denis,
>> What is the difference of required by users functionality with TTL cache
>> expiration?
>> By some posts I can suppose TTL cache is compatible with native
>> persistence.
>> Sincerely,
>> Dmitriy Pavlov
>> сб, 18 нояб. 2017 г. в 0:41, Denis Magda <dmagda@apache.org>:
>>> Igniters,
>>> I’ve been talking to many Ignite users here and there who are already on
>>> Ignite persistence or consider to turn it on. The majority of them are more
>>> than satisfied with its current state and provided capabilities. That’s is
>>> really good news for us.
>>> However, I tend to come across the people who ask about
>>> eviction/expiration policies for the persistence itself. Had around 6
>>> conversation about the topic this month only.
>>> Usually the requirement is connected with a streaming use case. When an
>>> application streams a lot of data (IoT, metrics, etc.) to the cluster but
>>> the data becomes stale in some period of time (day, couple of days, etc.).
>>> The user doesn’t want to waste the disk space and needs to simple purge the
>>> data from there.
>>> My suggestion here is to create a timer task that will remove the stale
>>> data from the cluster. However, since the demand is growing probably it’s a
>>> good time to discuss a feasibility of this feature.
>>> Alex G, as the main architect of the persistence, could you share your
>>> thoughts on this? What will it cost to us to support eviction/expiration
>>> for the persistence?
>>> —
>>> Denis

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