[jira] [Commented] (OAK-1979) prevent simultaneous installation of different instances

["Julian Reschke (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/OAK-1979?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14519178#comment-14519178 ] 

Julian Reschke commented on OAK-1979:
-------------------------------------

For RDBMK: creating the DBs is unlikely to cause a problem (the DocumentStore will only create tables when they are missing).

With respect to "application installation" - how is the persistence supposed to know what it is, and when it is done? Do we need a new API here?

> prevent simultaneous installation of different instances
> --------------------------------------------------------
>
>                 Key: OAK-1979
>                 URL: https://issues.apache.org/jira/browse/OAK-1979
>             Project: Jackrabbit Oak
>          Issue Type: Improvement
>          Components: mongomk, rdbmk
>            Reporter: Michael Marth
>            Priority: Minor
>              Labels: resilience
>
> For MongoMK and RDBMK: if the repository is empty and 1 Oak instance starts to do an initial application installation (creating dbs, adding nodetypes, etc) we should prevent a second instance from doing the same simultaneously. This would happen e.g. when 2 instances are started at the same time.
> The 1st instance could set a flag "initializing" that gets removed afterwards. The 2nd instance should wait or abort.
> In case the 1st instance does not finish the installation and does not remove the flag we should have some "force install" behavior for the second instance (alternatively we could prompt the user to drop the half-filled DBs).



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