[CALCITE-783] Infer collation of Project using monotonicity

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.4.0-incubating
• Component/s: core
• Assignee: Julian Hyde
• Reporter: Milinda Pathirage
• Created: 03/Jul/15 15:47
• Updated: 11/Jan/16 20:51
• Resolved: 21/Jul/15 04:47

Description

Current implementation of RelMdCollation#project doesn't handle function expressions and because of that we loose any collation metadata related to monotonic expressions which can be useful for generating streaming query execution plans involving tumbling windows.

Following is how current code looks like (RelMdCollation):

185: for (Ord<RexNode> project : Ord.zip(projects)) {
186: if (project.e instanceof RexInputRef)

{ 187: targets.put(((RexInputRef) project.e).getIndex(), project.i); 188: }

189: }

We only handle projects of type RexInputRef. But to support monotonic expressions we should laso handle projects of type RexCall.

Issue Links

• incorporates: CALCITE-742 RelFieldTrimmer throws NoSuchElementException in some cases
• is blocked by: CALCITE-784 LogicalAggregate's create method discards any collation traits from input