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https://issues.apache.org/jira/browse/PHOENIX-5562?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kadir OZDEMIR updated PHOENIX-5562:
-----------------------------------
Description:
>From the consistent secondary indexing design (PHOENIX-5156) perspective, two
>or more updates on the same row are concurrent updates if and only if all of
>them have acquired the row lock for reading the data table row before any of
>of them acquires the row lock the second time for updating the data table. In
>other words, all of them are in the first update phase concurrently.
In the current implementation, these updates can detect the existence of each
other in two places
(1) after acquiring the lock to read the existing row on the data table
(2) after acquiring the row lock to update the data table
This allows all the concurrent updates to detect each other and complete first
two update phases but skip the last update phase. This means the data table row
will be updated by these updates but the corresponding index table rows will be
left with the unverified status. Then, the read repair process will repair
these unverified index rows during scans. Although this behavior leads to the
correct end result, ideally we would like to see that the concurrent update
with most recent timestamp proceeds with the last phase instead of leaving the
index rows in the unverified status. This would reduce the number of unverified
rows due to concurrent updates.
was:
>From the consistent secondary indexing design (PHOENIX-5156) perspective, two
>or more updates on the same row are concurrent updates if and only if all of
>them have acquired the row lock for reading the data table row before any of
>of them acquires the row lock the second time for updating the data table. In
>other words, all of them are in the first update phase concurrently.
In the current implementation, these updates can detect the existence of each
other in two places
(1) after acquiring the lock to read the existing row on the data table
(1) after acquiring the row lock to update the data table
This allows all the concurrent updates to detect each other and complete first
two update phases but skip the last update phase. This means the data table row
will be updated by these updates but the corresponding index table rows will be
left with the unverified status. Then, the read repair process will repair
these unverified index rows during scans. Although this behavior leads to the
correct end result, ideally we would like to see that the concurrent update
with most recent timestamp proceeds with the last phase instead of leaving the
index rows in the unverified status. This would reduce the number of unverified
rows due to concurrent updates.
> The last concurrent update can complete the last write phase
> ------------------------------------------------------------
>
> Key: PHOENIX-5562
> URL: https://issues.apache.org/jira/browse/PHOENIX-5562
> Project: Phoenix
> Issue Type: Improvement
> Affects Versions: 5.1.0
> Reporter: Kadir OZDEMIR
> Assignee: Kadir OZDEMIR
> Priority: Major
>
> From the consistent secondary indexing design (PHOENIX-5156) perspective, two
> or more updates on the same row are concurrent updates if and only if all of
> them have acquired the row lock for reading the data table row before any of
> of them acquires the row lock the second time for updating the data table. In
> other words, all of them are in the first update phase concurrently.
> In the current implementation, these updates can detect the existence of each
> other in two places
> (1) after acquiring the lock to read the existing row on the data table
> (2) after acquiring the row lock to update the data table
> This allows all the concurrent updates to detect each other and complete
> first two update phases but skip the last update phase. This means the data
> table row will be updated by these updates but the corresponding index table
> rows will be left with the unverified status. Then, the read repair process
> will repair these unverified index rows during scans. Although this behavior
> leads to the correct end result, ideally we would like to see that the
> concurrent update with most recent timestamp proceeds with the last phase
> instead of leaving the index rows in the unverified status. This would reduce
> the number of unverified rows due to concurrent updates.
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