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From Jordan Zimmerman <jor...@jordanzimmerman.com>
Subject Re: Dealing with old delivered requests in memory
Date Fri, 18 Mar 2016 16:40:28 GMT
ZooKeeper stores the entire database in memory. Logs are for durability only. ZNodes exist
until deleted.

-Jordan

> On Mar 18, 2016, at 11:38 AM, ibrahim El-sanosi <ibrahimsabattt@gmail.com> wrote:
> 
> Thank you for replaying.
> 
> 
> Take this example, Zookeeper started on 1/1/2015, and assume ZK servers are
> never crashed. Also, the ZK are very busy, reciveing continusly write
> requests from clients and accordingly snapshots are generated overtime. On
> 1/3/2015, what  Znodes will be in memory data tree? do all Znodes still
> store in memory (from 1/1/2015 to 1/3/2015) as there is no crashed occur.
> Or Dsnapshhot is taken the data tree is
> 
> 
> Note that  I am not asking about data in log or snapshoot. I am asking
> about the current data in memory.
> 
> On Fri, Mar 18, 2016 at 4:12 PM, Flavio Junqueira <fpj@apache.org> wrote:
> 
>> Hi Ibrahim,
>> 
>> Are you asking about how we compact old logs? We do it by taking snapshots
>> so that upon recovery, we only load the latest snapshot and replay the txn
>> log from the snapshot tag. The snapshot tag is the last zxid committed when
>> we start producing the snapshot.
>> 
>> We don't actually delete anything, though, unless you intentionally turn
>> on auto purge:
>> 
>> https://zookeeper.apache.org/doc/trunk/zookeeperAdmin.html#sc_administering
>> <
>> https://zookeeper.apache.org/doc/trunk/zookeeperAdmin.html#sc_administering
>>> 
>> 
>> -Flavio
>> 
>>> On 18 Mar 2016, at 16:05, ibrahim El-sanosi <ibrahimsabattt@gmail.com>
>> wrote:
>>> 
>>> Hi all,
>>> 
>>> Assume the Zookeeper have been running for about one year (from 1/1/2015
>>> until now), how does ZooKeeper deal with old delivered write requests (To
>>> optimize a memory used) (say from 1/1/2015 to 03/04/2015). I am assuming
>>> the old delivered request are no longer used.
>>> 
>>> On the other words, what strategy ZK does to find and delete unused
>> Znodes?
>>> 
>>> Ibrahim
>> 
>> 


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