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From Øystein Grøvlen (JIRA) <j...@apache.org>
Subject [jira] Commented: (DERBY-2977) Replication: Add a ReplicationMaster controller that will manage replication on the master side
Date Tue, 04 Sep 2007 11:28:58 GMT

    [ https://issues.apache.org/jira/browse/DERBY-2977?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12524680

Øystein Grøvlen commented on DERBY-2977:

Jørgen Løland (JIRA) wrote:
> Thanks for reviewing the patch, Øystein.
> The attached patch, v1b, addresses your comments in the following way:
>> 1. Why do you need to expose LogToFile#logBufferSize outside the
>>    class?  The Logger used by transactions handles the buffer size
>>    dynamically, why cannot this be done in this case, too?
> Actually, as far as I can tell, the log buffer used by
> transactions (LogAccessFile) uses the same LogToFile#buffersize
> exposed here. Is there another file I should look at? I use this
> buffer size because I cannot think of any other size that would
> be better in the general case. I can change this if you have any
> suggestions for an appropriate size. If so, MasterFactory should
> probably store the default size as a static final variable. Left
> unchanged in v1b since I can't think of a better alternative.

Sorry, I thought there was one buffer per log record, which is similar
to FileLogger which has a dynamic buffer size.  Still, I do not think
that what is the optimal buffer size for writing to disk is
necessarily the best buffer size when sending messages over the
network.  I would think that should be independent of each other.

The rest of the changes looks very good, but I have one question on
flushedTo: It seems to be the assumption that a log record should not
be sent to the slave before it is written to disk?  Is this a
necessary requirement?  If yes, maybe that should be documented too.

> Replication: Add a ReplicationMaster controller that will manage replication on the master
> -----------------------------------------------------------------------------------------------
>                 Key: DERBY-2977
>                 URL: https://issues.apache.org/jira/browse/DERBY-2977
>             Project: Derby
>          Issue Type: Sub-task
>          Components: Services
>    Affects Versions:
>            Reporter: Jørgen Løland
>            Assignee: Jørgen Løland
>         Attachments: derby_2977_1.diff, derby_2977_1.stat, derby_2977_1b.diff, derby_2977_1b.stat
> The replication master role includes many tasks:
> * set up a network connection to the slave
> * sending the database to the slave before starting replication
> * make sure that log records are appended to the network buffer, and that the log is
later sent to the slave
> * etc
> This issue is for adding a controller that will start/stop/initiate all services needed
for the replication master role.

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