Julian Hyde created CALCITE-5105:
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Summary: Add MEASURE type and AGGREGATE aggregate function
Key: CALCITE-5105
URL: https://issues.apache.org/jira/browse/CALCITE-5105
Project: Calcite
Issue Type: Bug
Reporter: Julian Hyde
In CALCITE-4496 we propose adding measures to SQL, and an "AS MEASURE"
sub-clause to the SELECT clause so that you can define measures. This change is
a first step in that direction: namely the ability to define the columns are
measures and use validate queries that use measures.
This change adds a {{MEASURE}} type, which is parameterized with the value
type, so that in RelNode-and-RexNode-land a measure column whose value is of
type {{INTEGER}} would have type {{MEASURE<INTEGER>}}. (In SqlNode-land its
type would be {{INTEGER}} and we would tell that it was a measure by some other
means.)
This change also adds an aggregate function called {{AGGREGATE}} that evaluates
measures in the current {{GROUP BY}} context. (You can think of this as letting
the measures roll themselves up as only they know how. For example, if the
{{sum_price}} measure is defined as {{SUM(price)}} then if I write
{{AGGREGATE(sum_price)}} in my query it's as if I wrote {{SUM(price)}}. But we
also support measures that have more complex formulas.)
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