Julian Hyde created CALCITE-2540:
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Summary: Streaming Sort relational operator
Key: CALCITE-2540
URL: https://issues.apache.org/jira/browse/CALCITE-2540
Project: Calcite
Issue Type: Bug
Reporter: Julian Hyde
Assignee: Julian Hyde
Add a sub-class of the Sort operator that takes advantage of the fact that its
input is sorted on a prefix of the key.
For example, given the relation "select * from t order by x" it is easier to
compute "select * from t order by x, y". The Sort operator can spot when the
value of "x" changes, flush all of its input, and start sorting on values of
"y" until the value of "x" changes again.
I don't know whether to call this "weak" sort or "partial sort". It's
"streaming" in the sense that it can produce output before it sees all of the
input (and therefore requires less memory); it is not just applicable to
streaming SQL.
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