Github user zellerh commented on a diff in the pull request:
https://github.com/apache/incubator-trafodion/pull/380#discussion_r56228136
--- 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 --
Can you explain this again, I would have thought it's the other way round:
With non-aligned format, if we omit any column then we run a chance of seeing
the value of an older row. Is that a "feature"? If so and if
TRAF_UPSERT_WITH_INSERT_DEFAULT_SEMANTICS is set to ON, will that cause a
difference between the behavior with aligned and non-aligned format? My
apologies, I think you explained this to me before.
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