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https://issues.apache.org/jira/browse/DERBY-4197?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jørgen Løland updated DERBY-4197:
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Summary: Simplify initialization of replication (was: Simplify initiation
of replication)
> Simplify initialization of replication
> --------------------------------------
>
> Key: DERBY-4197
> URL: https://issues.apache.org/jira/browse/DERBY-4197
> Project: Derby
> Issue Type: New Feature
> Components: Replication
> Affects Versions: 10.6.0.0
> Reporter: Jørgen Løland
> Priority: Minor
>
> Starting Derby replication is brittle; you need to perform multiple steps in
> exact order. Furthermore, the steps involves freezing the database on the
> master Derby instance the time it takes to copy the database to the slave
> node.
> A much simpler way to start replication would be:
> 1) Make an online backup of the database on the master Derby instance. Enable
> log archiving.
> 2) Copy the backup to the slave node while the master Derby instance
> continues to handle transactions
> 3) Boot the slave database in slave mode.
> 4) Master sends all log written since the backup was made, or from a
> specified log instant (a number that can be specified as an option to either
> the startSlave or startMaster command?).
> The main implementation effort is in step 4, because this step requires the
> master derby instance to read and send log records that are on disk. This
> differs from the current replication code that captures log records on the
> master as they are about to be written to disk (i.e., replication does not
> read files).
> Since the master instance is supposed to continue transaction processing, it
> will write to the latest log file while the replication thread will have to
> read log files (including the currently open one). The Derby code that reads
> log files is written to handle a single thread (the recovery thread) only in
> the current implementation.
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