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From "V.Narayanan (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-3562) Number of log files (and log dir size) on the slave increases continuously
Date Fri, 21 Mar 2008 07:59:24 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3562?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12581024#action_12581024
] 

V.Narayanan commented on DERBY-3562:
------------------------------------

Not sure if the analysis here points at the rate of increase in the slave or the increase
in the slave relative to the master. 

But isn't an increase in the log size of a slave expected, because the Slave receives log

records from the master and use LogToFile#appendLogRecord to write these to disk. 
So basically the slave uses the logs received from the master to recover and move to a 
transaction consistent state.

Incase you have not seen the following points from Derby-3071 (Modify logging subsystem for
slave replication mode)

* SlaveFactory (DERBY-3021) will receive log records from the master and use LogToFile#appendLogRecord
to write these to disk. While in slave mode, only SlaveFactory will be allowed to append log
records.
* The thread running LogToFile#recover will recover (redo) one log file at a time (like now),
but will not be allowed to open a log file X until that file is no longer being written to.
Thus, while appenLogFile writes to logX.dat, recover will be allowed to read all log files
up to and including logX-1.dat but will then have to wait until appendLogRecord starts writing
to logX+1.dat.

> Number of log files (and log dir size) on the slave increases continuously
> --------------------------------------------------------------------------
>
>                 Key: DERBY-3562
>                 URL: https://issues.apache.org/jira/browse/DERBY-3562
>             Project: Derby
>          Issue Type: Bug
>          Components: Replication
>    Affects Versions: 10.4.0.0, 10.5.0.0
>         Environment: -
>            Reporter: Ole Solberg
>         Attachments: master_slave-db_size-6.jpg
>
>
> I did a simple test inserting tuples in a table during replication:
> The attached file 'master_slave-db_size-6.jpg' shows that 
> the size of the log directory (and number of files in the log directory)
> increases continuously during replication, while on master the size 
> (and number of files) never exceeds ~12Mb (12 files?) in this scenario.
> The seg0 directory on the slave stays at the same size as the master 
> seg0 directory.

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