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From "Alicia Ying Shu (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-2221) Option to make data regions not writable when index regions are not available
Date Mon, 09 Nov 2015 22:55:11 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-2221?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14997576#comment-14997576
] 

Alicia Ying Shu commented on PHOENIX-2221:
------------------------------------------

[~jamestaylor]
>don't assume the type of the delegator to be KillServerOnFailurePolicy
KillServerOnFailurePolicy has the implementation that when updating index failed, abort the
region server. Need KillServerOnFailurePolicy for not reimplementing abort() when catching
failed exception.

>I don't understand why any changes are necessary to PhoenixIndexCodec
There are three possible values for INDEX_RECOVERY_FAILURE_POLICY_KEY: null, ReadableIndexFailedPolicy
and default(PhoenixIndexFailedPolicy). Just use IndexFailurePolicy.class.getName() will not
set the correct value for IndexWriter.INDEX_FAILURE_POLICY_CONF_KEY which is used for indexer
committer later to determine the policy.

>to create a new PIndexState.BLOCKED value to key off of, and then let the index state
transition from BLOCKED to ACTIVE once the partial index rebuild is complete.
The reason we used PIndexState.READABLE is that during index rebuild, index is not blocked
for read. It is still readable. Only the writes to data table are blocked. 

>Don't understand the changes to QueryOptimizer. An index needs to be ACTIVE in order for
it to be used. Why the check for READABLE?
During index rebuild, index is readable. When choosing a plan for a scan submitted during
index rebuild, if an index is in READABLE state, we can choose index scan since there is no
new data written except those failed ones. This applies to those applications that can tolerate
minor data loss during a minimum time. 





> Option to make data regions not writable when index regions are not available
> -----------------------------------------------------------------------------
>
>                 Key: PHOENIX-2221
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-2221
>             Project: Phoenix
>          Issue Type: Improvement
>            Reporter: Devaraj Das
>            Assignee: Alicia Ying Shu
>         Attachments: PHOENIX-2221-v1.patch, PHOENIX-2221-v2.patch, PHOENIX-2221.patch
>
>
> In one usecase, it was deemed better to not accept writes when the index regions are
unavailable for any reason (as opposed to disabling the index and the queries doing bigger
data-table scans).
> The idea is that the index regions are kept consistent with the data regions, and when
a query runs against the index regions, one can be reasonably sure that the query ran with
the most recent data in the data regions. When the index regions are unavailable, the writes
to the data table are rejected. Read queries off of the index regions would have deterministic
performance (and on the other hand if the index is disabled, then the read queries would have
to go to the data regions until the indexes are rebuilt, and the queries would suffer).



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