MEASURE type and AGGREGATE aggregate function
Can I get a review for https://github.com/apache/calcite/pull/2965 / https://issues.apache.org/jira/browse/CALCITE-5105? It's the first change in what is - in my opinion - a major extension to SQL, namely being able to define expressions in queries and views and have those expressions 'expand' in the context where they are used. It's something that BI tools and multidimensional databases do, but it is not allowed by the conventional rules of SQL. This change is fairly modest, adding a MEASURE type so that we can represent measures internally. I believe that I have added sufficient switches so that people who don't want these extensions in their SQL dialect don't get them. A later case, https://issues.apache.org/jira/browse/CALCITE-4496, will allow you to define measures as part of a query and have them inlined when you use them in an enclosing query. That case is quite a long way from completion. Julian
[jira] [Created] (CALCITE-5105) Add MEASURE type and AGGREGATE aggregate function
Julian Hyde created CALCITE-5105:
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}}. (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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