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From anoopsharma00 <...@git.apache.org>
Subject [GitHub] incubator-trafodion pull request: JIRA TRAFODION-2006 Hive table structure a...
Date Tue, 31 May 2016 19:24:28 GMT
Github user anoopsharma00 commented on a diff in the pull request:

    https://github.com/apache/incubator-trafodion/pull/511#discussion_r65246611
  
    --- Diff: core/sql/optimizer/NATable.cpp ---
    @@ -7308,6 +7308,16 @@ NATable * NATableDB::get(const ExtendedQualName* key, BindWA* bindWA,
NABoolean
          }
       }
     
    +  // the reload cqd will be set during aqr after compiletime and runtime
    +  // timestamp mismatch is detected.
    +  // If set, reload hive metadata.
    +  if ((cachedNATable->isHiveTable()) &&
    +      (CmpCommon::getDefault(HIVE_DATA_MOD_CHECK) == DF_ON) &&
    +      (CmpCommon::getDefault(TRAF_RELOAD_NATABLE_CACHE) == DF_ON))
    --- End diff --
    
    For non-hive trafodion tables, query invalidation feature detects when a particular
    table structure has changed and invalidates natable for that table only.
     
    For hive tables, table modification detection is based on detection of timestamp 
    change of the hive dirs since query invalidation feature does not apply to hive
    tables as they could be created/populated from outside of trafodion. 
    Also unlike traf tables, we need to know when data has changed for a
    hive table as optimizer uses that information to generate data access maps.
    
    So aqr is done when timestamp change is detected for hive data/struct dirs.
    AQR granularity is at query level and NATables for all tables that are part of the 
    query which is being AQR'd will be reloaded. 
    Tables that are not part of that query will not be reloaded.
    



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