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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-4196) Document initiation of replication from cleanly shut down database
Date Mon, 13 Jul 2009 18:11:14 GMT

    [ https://issues.apache.org/jira/browse/DERBY-4196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12730436#action_12730436
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Knut Anders Hatlen commented on DERBY-4196:
-------------------------------------------

Thanks Kim!

startMaster=true will boot the database if it's not already booted. Since we don't want to
mention the freeze step anymore, we could probably skip the sentence about startMaster=true
unfreezing the database. The paragraph starting with "If any unlogged operations are running"
will not make much sense either if we make these changes, and can be removed (no unlogged
operations can be running in a database that's not booted).

In the reference manual, I think this change must be made:

Before you specify this attribute, you must boot the database on the master system, freeze
it, perform a file system copy (...)
-> (...) this attribute, you must cleanly shut down the database on the master system,
perform a file system copy (...)

I don't know if we should remove the paragraph about unlogged operations from the reference
manual, or if we should just make it less prominent. It is still the behaviour of startMaster=true
if the database is already booted when it's invoked, so it might still make sense to mention
it. Perhaps just change the start first sentence in that paragraph to "If the master database
is already booted and any unlogged operations are running"?

> Document initiation of replication from cleanly shut down database
> ------------------------------------------------------------------
>
>                 Key: DERBY-4196
>                 URL: https://issues.apache.org/jira/browse/DERBY-4196
>             Project: Derby
>          Issue Type: Improvement
>          Components: Documentation, Replication
>    Affects Versions: 10.4.1.3
>            Reporter: Knut Anders Hatlen
>            Assignee: Kim Haase
>            Priority: Minor
>
> The admin guide describes how to start replication.
> http://db.apache.org/derby/docs/dev/adminguide/cadminreplicstartrun.html
> It describes two steps that must be performed before the database is copied from the
master to the slave:
> 1. Boot the database on the master system
> 2. Freeze the database (CALL SYSCS_UTIL.SYSCS_FREEZE_DATABASE())
> Those two steps could be replaced with a single step:
> 1-2) Make sure the database on the master system is shut down cleanly
> This works because then there is no recovery to be performed when the database later
is booted in master mode, and neither the log nor the database will be modified during boot,
so the master database will stay completely in sync with the slave.
> Advantages with the alternative procedure are:
> - no need to keep a process running with the database booted and frozen while copying
the database from the master system to the slave system
> - uncommitted transactions that are active at the time of the copying won't cause any
problems (DERBY-3896)

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