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From "James Taylor (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-3823) Force cache update on MetaDataEntityNotFoundException
Date Fri, 26 May 2017 23:23:04 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-3823?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16027010#comment-16027010
] 

James Taylor commented on PHOENIX-3823:
---------------------------------------

Thanks for the update, [~sukunaidu@gmail.com]. You'd need to create a new visitor to visit
all instances of NamedTableNode as it could be a self join (or correlated subquery against
the same table). This would end up being more code than just modifying createTableRef. It's
a pretty straightforward change - just store mutatingTable in a member variable. It'll be
null most times (except for delete and upsert select).

> Force cache update on MetaDataEntityNotFoundException 
> ------------------------------------------------------
>
>                 Key: PHOENIX-3823
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-3823
>             Project: Phoenix
>          Issue Type: Sub-task
>    Affects Versions: 4.10.0
>            Reporter: James Taylor
>            Assignee: Maddineni Sukumar
>             Fix For: 4.11.0
>
>         Attachments: PHOENIX-3823.patch, PHOENIX-3823.v2.patch, PHOENIX-3823.v3.patch,
PHOENIX-3823.v4.patch, PHOENIX-3823.v5.patch, PHOENIX-3823.v6.patch
>
>
> When UPDATE_CACHE_FREQUENCY is used, clients will cache metadata for a period of time
which may cause the schema being used to become stale. If another client adds a column or
a new table or view, other clients won't see it. As a result, the client will get a MetaDataEntityNotFoundException.
Instead of bubbling this up, we should retry after forcing a cache update on the tables involved
in the query.
> The above works well for references to entities that don't yet exist. However, we cannot
detect when some entities are referred to which no longer exists until the cache expires.
An exception is if a physical table is dropped which would be detected immediately, however
we would allow queries and updates to columns which have been dropped until the cache entry
expires (which seems like a reasonable tradeoff IMHO. In addition, we won't start using indexes
on tables until the cache expires.



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