[CALCITE-2654] In RelBuilder, add a fluent API for building complex aggregate calls

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.18.0
• Assignee: Julian Hyde
• Reporter: Julian Hyde
• Created: 04/Nov/18 04:04
• Updated: 23/Dec/18 00:12
• Resolved: 08/Nov/18 18:05

Description

In RelBuilder, add a fluent API for building complex aggregate calls. Currently, the RelBuilder.aggregateCall has arguments aggFunction, distinct, approximate, filter, orderKeys, alias and operands, and in CALCITE-2224 we're adding orderKeys. You have to specify all of them, whether or not your function is DISTINCT or has a FILTER(WHERE) clause.

The new API would be simple:

• RelBuilder.aggregateCall(op, operands)
• RelBuilder.sum(operand)
• RelBuilder.count(operands)
• RelBuilder.min(operands)

and so forth. Each of these returns an AggCall, and we propose to add fluent methods to that:

• AggCall.distinct(boolean)
• AggCall.approximate(boolean)
• AggCall.alias(String)
• AggCall.filter(RexNode)
• AggCall.sort(RexNode...) (for CALCITE-2224)

Thus you can write builder.sum(builder.field("SAL)).distinct(true).alias("SUM_SAL").