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From selvaganesang <...@git.apache.org>
Subject [GitHub] incubator-trafodion pull request: [TRAFODION-1887] Upsert into ali...
Date Tue, 15 Mar 2016 21:35:07 GMT
Github user selvaganesang commented on a diff in the pull request:

    https://github.com/apache/incubator-trafodion/pull/380#discussion_r56245070
  
    --- Diff: core/sql/optimizer/BindRelExpr.cpp ---
    @@ -10171,17 +10164,26 @@ matched clause of merge). If the upsert caused a row to be updated
in the
     base table then the old version of the row will have to be deleted from 
     indexes, and a new version inserted. Upsert is being transformed to merge
     so that we can delete the old version of an updated row from the index.
    +
    +Upsert is also converted into merge when there are omitted cols with default values and

    +TRAF_UPSERT_WITH_INSERT_DEFAULT_SEMANTICS is set to  OFF in case of aligned format table
or 
    +omitted current timestamp cols in case of non-aligned row format
    --- End diff --
    
    In fact, we always generate assignment for all columns at the time of upsert even if the
column is omitted in both formats. We had to do this because these columns need to flow to
IM operators. In case of non-aligned format, these columns are removed from put into hbase
at the executor. But these columns would exist in the raw index table in hbase if we happen
to have an index on the omitted column. See PR #340
    
     For the first change request: If we always assign the current timestamp, what happens
if the row exists. Won't we replace it the current timestamp even when some other column is
updated or upserted.
    
    For the second change request: When the CQD TRAF_UPSERT_WITH_INSERT_DEFAULT_SEMANTICS
 (aligned format) is set to ON, we just don't change it merge if there are no secondary indexes.

    
    For non-aligned format, I need to recheck if the same CQD can be used. Though I had concluded
we need to populate the default values for the non-aligned format earlier, there might be
a way out of this. We can file a JIRA for it.


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