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Posted to user@ignite.apache.org by tarunk <ta...@gmail.com> on 2019/05/22 15:10:16 UTC

PartitionLossPolicy | IGNORE

Hi All, 

While going through Apache-Ignite's PartitionLossPolicy : IGNORE, the
default one for which I found 2 explanation and having some doubt about
these. 

As per API doc:
https://ignite.apache.org/releases/latest/javadoc/org/apache/ignite/cache/PartitionLossPolicy.html
If partition is lost, reset it's state and do not clear intermediate data.
The result of reading from a previously lost and not cleared partition is
undefined and may be different on different nodes in the cluster. 

As per https://apacheignite.readme.io/docs/partition-loss-policies
this mode never marks a lost partition as lost, pretending that no partition
loss has happened and clearing the partition loss state right away.
Technically, the partition will not be added to the collection of
lostPartitions which is the main difference from READ_WRITE_ALL mode. 

From the API doc explanation, it looks like that we might get inconsistent
result on different nodes by reading from a previously lost partition.
While from standard docs on website, this is not clearly defined if its
safe, That weather we will consistently just get null on reading from a
previously lost on all nodes or it will be some inconsistent behavior. 

Can we please get confirmation which interpretation make more sense ?



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Re: PartitionLossPolicy | IGNORE

Posted by tarunk <ta...@gmail.com>.
Thank you Igor for the quick response.

Shall we expect this to be corrected in redame.io doc to make it consistent
with API doc and avoid the confusion ?



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Re: PartitionLossPolicy | IGNORE

Posted by ibelyakov <ig...@gmail.com>.
Hi,

Looks like next part is missing for IGNORE policy description in readme.io
documentation:
"The result of reading from a lost partition is undefined and may be
different on different nodes in the cluster."

There is no guarantee for IGNORE policy that reading from the lost partition
will return "null" on all nodes.

Regards,
Igor



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