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From Denis Magda <dma...@apache.org>
Subject Re: Unclear configuration parameters of Persistent Store
Date Fri, 26 May 2017 21:06:27 GMT
Alex G.,

> * PersistentStoreConfiguration.setWalHistorySize
> * PersistentStoreConfiguration.setWalArchivePath

I could figure out the goal of these two parameters below referring to the store architecture
guide [1] and updated the Java docs.

> PersistentStoreConfiguration.setLockWaitTime

However, it’s still not obvious how to document this lockWaitTime. Plus, the checkpointing
description in [1] confused me a bit. I assumed that the checkpointing is used to unwind the
WAL only but know I see that it literally copies data from the memory to disk. What do we
store in WAL then if it’s not a delta of an update?

In general, I would need your help to finalize the checkpoint section and update the WAL section
in the high-level user documentation I’ve been working on:

[1] https://cwiki.apache.org/confluence/display/IGNITE/Persistent+Store+Architecture#PersistentStoreArchitecture-Checkpointing


> On May 25, 2017, at 6:06 PM, Denis Magda <dmagda@apache.org> wrote:
> Igniters,
> I’ve been working on the documentation for the Persistent Store fixing Java Doc in
> https://apacheignite.readme.io/v2.0/docs/distributed-persistent-store <https://apacheignite.readme.io/v2.0/docs/distributed-persistent-store>
> However, there are several configuration parameters of PersistentStoreConfiguration that
don’t make sense to me:
> * PersistentStoreConfiguration.setLockWaitTime
> * PersistentStoreConfiguration.setWalHistorySize
> * PersistentStoreConfiguration.setWalArchivePath (here I can get what this "Full WAL
segments will be copied to this directory before reuse.” means to me as to the end user)
> Alex G., as the store architect, please document those methods so that the users can
understand what are they for and when they should be used. Also it will be great if you look
through the rest of the parameters.
> Finally, I do remember there was a way to do the writes to the store in async or sync
mode but I can’t find any parameter to tweak the behavior. Is there any other configuration
API I’m not aware of?
> —
> Denis

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