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https://issues.apache.org/jira/browse/PHOENIX-5528?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17076775#comment-17076775
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Hadoop QA commented on PHOENIX-5528:
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{color:red}-1 overall{color}. Here are the results of testing the latest
attachment
http://issues.apache.org/jira/secure/attachment/12983110/PHOENIX-5528.master.001.patch
against master branch at commit b3497876a404828c6486ffc1e2e1957a007abeb6.
ATTACHMENT ID: 12983110
{color:green}+1 @author{color}. The patch does not contain any @author
tags.
{color:red}-1 tests included{color}. The patch doesn't appear to include
any new or modified tests.
Please justify why no new tests are needed for this
patch.
Also please list what manual steps were performed to
verify this patch.
{color:red}-1 patch{color}. The patch command could not apply the patch.
Console output:
https://builds.apache.org/job/PreCommit-PHOENIX-Build/3727//console
This message is automatically generated.
> Race condition in index verification causes multiple index rows to be
> returned for single data table row
> --------------------------------------------------------------------------------------------------------
>
> Key: PHOENIX-5528
> URL: https://issues.apache.org/jira/browse/PHOENIX-5528
> Project: Phoenix
> Issue Type: Bug
> Reporter: Vincent Poon
> Assignee: Kadir OZDEMIR
> Priority: Major
> Attachments: PHOENIX-5528.master.001.patch
>
>
> Warning: This is an artificially generated scenario that likely has a very
> low probability of happening in practice. But a race condition nevertheless.
> Unfortunately I don't have a test case, but was able to produce this by
> debugging a local regionserver and adding breakpoints at the right places to
> produce the ordering here.
> The core problem is that when we do an update to the data table, we produce
> two unverified index rows at first. When we scan both of these index rows
> and attempt to verify via rebuilding the data table row, we cannot guarantee
> that both verifications happen before the data table update, or both happen
> after the data table update.
> I use multiple index regions here to demonstrate, but I believe it could
> happen within a single region as well.
> Steps:
> 1) Create a test table with "pk" and "indexed_val" columns, and a global
> index on "indexed_val".
> 2) upsert into test values ('test_pk', 'test_val');
> 3) Split the index table on 'test_pk':
> hbase shell: split 'test_index', 'test_pk'.
> This creates two regions, call them regionA and regionB (which holds the
> existing index row)
> 3) start an update: upsert into test values ('test_pk', 'new_val');
> The first thing the indexing code does is create two unverified index
> rows: one is a new version of the existing index row, and the other is for
> the new indexed value.
> We pause the thread after this is done, before the row locks and data
> table write happens.
> 4) select indexed_val from test;
> This scans both the index regions in parallel. Each scan picks up a
> unverified row in its region. We pause in GlobalIndexChecker.
> Let the regionB scan proceed. It will attempt to rebuild the data table
> row. The data table still has 'test_val' as the indexed value. The rebuild
> succeeds.
> scan on regionA still paused.
> 5) The original update proceeds to update the data table indexed value to
> 'new_val'.
> 6) The scan on regionA proceeds, and attempted to rebuild the data table row.
> The rebuild succeeds with 'new_val' as the indexed value.
> 7) Both 'test_val' and 'new_val' are returned to the client, because both
> rebuilds succeeded.
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