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From "Sun Rui (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-5256) A map join operator may have in-consistent output row schema with the common join operator which it will replace
Date Tue, 10 Sep 2013 12:56:52 GMT

     [ https://issues.apache.org/jira/browse/HIVE-5256?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Sun Rui updated HIVE-5256:
--------------------------

    Status: Patch Available  (was: Open)
    
> A map join operator may have in-consistent output row schema with the common join operator
which it will replace
> ----------------------------------------------------------------------------------------------------------------
>
>                 Key: HIVE-5256
>                 URL: https://issues.apache.org/jira/browse/HIVE-5256
>             Project: Hive
>          Issue Type: Bug
>          Components: Query Processor
>    Affects Versions: 0.11.0
>            Reporter: Sun Rui
>
> When generating a common join operator, Semantic Analyzer gets the input RowResolver
of each parent operators. It then uses the following piece of code to interate the tables
from the RowResolver (refer to genJoinOperatorChildren()):
>         RowResolver inputRS = opParseCtx.get(input).getRowResolver();
>         Iterator<String> keysIter = inputRS.getTableNames().iterator();
> 		...
>         while (keysIter.hasNext()) {
>           String key = keysIter.next();
> Note that the interation order is not deterministic because of the current RowResolver
implementation:
>   private  HashMap<String, LinkedHashMap<String, ColumnInfo>> rslvMap;
>   ...
>   public Set<String> getTableNames() {
>     return rslvMap.keySet();
>   }
> Generally, the interation order has no problem. However, it may be problematic when a
common join operator is being converted to a map join operator.
> MapJoinProcessor.convertMapJoin():
>       RowResolver inputRS = opParseCtxMap.get(newParentOps.get(pos)).getRowResolver();
>       List<ExprNodeDesc> values = new ArrayList<ExprNodeDesc>();
>       Iterator<String> keysIter = inputRS.getTableNames().iterator();
>       while (keysIter.hasNext()) {
> The problem is that the table iteration order for a input RowResolver may be different
from that in the generation of the common join operator, which result in an in-consistent
output row schema. Thus wrong row schema may be input to child operators and will cause problems.
> I found this issue when running a TPC-DS query. And this issue happens to be exposed
due to HIVE-4078.
> The proposed fix is to change RowResolver to define rslvMap as LinkedHashMap instead
of HashMap. Thus the table iteration order of a RowResolver is fixed.

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