[
https://issues.apache.org/jira/browse/ZOOKEEPER-1001?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13009211#comment-13009211
]
Flavio Junqueira commented on ZOOKEEPER-1001:
---------------------------------------------
Ivan, the problem is that if you have no information on what entries have been
committed, the application process might end up reading one entry that has only
been partially written. For safety, the application has to implement a
mechanism to guarantee that it will only read committed entries, a la
TeaKeeper. The open call, however, is not aware of what the application is
doing, so it doesn't know if the application is really reading only committed
entries, and in that sense the open operation is unsafe.
Do you agree now or it is still unclear for you?
> Read from open ledger
> ---------------------
>
> Key: ZOOKEEPER-1001
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1001
> Project: ZooKeeper
> Issue Type: New Feature
> Components: contrib-bookkeeper
> Reporter: Flavio Junqueira
> Attachments: zk-1001-design-doc.pdf, zk-1001-design-doc.pdf
>
>
> The BookKeeper client currently does not allow a client to read from an open
> ledger. That is, if the creator of a ledger is still writing to it (and the
> ledger is not closed), then an attempt to open the same ledger for reading
> will execute the code to recover the ledger, assuming that the ledger has not
> been correctly closed.
> It seems that there are applications that do require the ability to read from
> a ledger while it is being written to, and the main goal of this jira is to
> discuss possible implementations of this feature.
--
This message is automatically generated by JIRA.
For more information on JIRA, see: http://www.atlassian.com/software/jira
