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Posted to dev@phoenix.apache.org by "Hudson (JIRA)" <ji...@apache.org> on 2016/08/06 06:54:20 UTC
[jira] [Commented] (PHOENIX-3156) DistinctPrefixFilter optimization
produces incorrect results with some non-pk WHERE conditions
[ https://issues.apache.org/jira/browse/PHOENIX-3156?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15410519#comment-15410519 ]
Hudson commented on PHOENIX-3156:
---------------------------------
SUCCESS: Integrated in Phoenix-master #1356 (See [https://builds.apache.org/job/Phoenix-master/1356/])
PHOENIX-3156 DistinctPrefixFilter optimization produces incorrect (larsh: rev 60b95f962e75d23553d53bc1f00373299b019e1b)
* phoenix-core/src/main/java/org/apache/phoenix/iterate/BaseResultIterators.java
* phoenix-core/src/it/java/org/apache/phoenix/end2end/DistinctPrefixFilterIT.java
> DistinctPrefixFilter optimization produces incorrect results with some non-pk WHERE conditions
> ----------------------------------------------------------------------------------------------
>
> Key: PHOENIX-3156
> URL: https://issues.apache.org/jira/browse/PHOENIX-3156
> Project: Phoenix
> Issue Type: Bug
> Reporter: Lars Hofhansl
> Assignee: Lars Hofhansl
> Priority: Blocker
> Fix For: 4.8.0
>
> Attachments: 3156-v2.txt, 3156.txt
>
>
> There's a corner case I found where a DISTINCT and GROUP BY query along a prefix of a compound row key might return incorrect results.
> The filter relies on seeing the _0 column absolutely last, and not seeing all Cells that should be filtered. That break in two scenarios:
> # we have a table with key (key1, key2, key3) and columns (c1 and c2). Now construct a WHERE <a clause that always matches c1>, <a clause that filters by c2) GROUP BY key1, key2. Now the filter would mis-skip when it sees the Cell for c1.
> # we force lower key column names. In that case those would sort after the _0 column. The DistinctPrefixFilter would see the _0 column first and skip.
> In both case we are effectively changing the order in which the filters are applied. The DistinctPrefixFilter is no longer for the row.
> I can fix #1 (by ignoring all Cells other than then _0 one). I do not know how to fix case #2.
> I think this is a blocker and we may have to undo the entire DISTINCT and GROUP BY prefix optimization.
> [~ankit@apache.org], [~giacomotaylor], [~samarthjain].
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