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https://issues.apache.org/jira/browse/PHOENIX-4487?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16302168#comment-16302168
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James Taylor commented on PHOENIX-4487:
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bq. However as discussed offline with [~twdsi...@gmail.com], we decided that
since we _officially_ support only 2 client backward versions, this should be
fine.
Please don't remove upgrade code without raising a discussion thread on the dev
list. Vendor distros often need upgrade code to remain longer than two minor
releases back due to the infrequency of their upgrade. For example, CDH will go
from 4.7 to 4.11. The HDP distro may be even further behind.
bq. The first line checks if SYSTEM.MUTEX table exists or not. This can be in 2
cases, either the table doesn't exist at all ot its being migrated to SYSTEM
namespace. There is no clear way of differentiating them and hence there arises
a plausible race condition here.
How is it better to go from an unlikely, possible race condition to always
throwing an exception and blocking the upgrade when the mutex table doesn't
exist? Please file a separate issue for handling the race condition properly.
This patch improves things at least.
bq. I don't see the need for checking if namespace mapping is enabled or not.
That check is because if namespaces are enabled, the earlier branch in the
upgrade code path is executed and ensures that the mutex table is created. I'll
add a comment.
bq. Also, how do we test this? Any UT or directly tried with a cluster?
Upgrade code needs to be manually checked. I'm hoping [~f.pompermaier] can help
test this once this patch is committed.
> Missing SYSTEM.MUTEX table upgrading from 4.7 to 4.13
> -----------------------------------------------------
>
> Key: PHOENIX-4487
> URL: https://issues.apache.org/jira/browse/PHOENIX-4487
> Project: Phoenix
> Issue Type: Bug
> Affects Versions: 4.14.0, 4.13.1, 4.13.2-cdh5.11.2
> Reporter: Flavio Pompermaier
> Assignee: James Taylor
> Attachments: PHOENIX-4487.patch
>
>
> Upgrading from the official Cloudera Parcel equipped with Phoenix 4.7 to the
> last unofficial parcel (4.13 on CDH 5.11.2) I had the same error of
> https://issues.apache.org/jira/browse/PHOENIX-4293 (apart from the fact that
> the from version was 4.7...).
> The creation of system.mutex table fixed the problem.
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