amaliujia commented on a change in pull request #1587: [CALCITE-3272] Support
TUMBLE as Table Value Function
URL: https://github.com/apache/calcite/pull/1587#discussion_r347158057
##########
File path:
core/src/main/java/org/apache/calcite/adapter/enumerable/RexToLixTranslator.java
##########
@@ -940,6 +956,49 @@ public static Expression translateLiteral(
return list;
}
+ private List<Expression> translateTableFunctionCall(RexCall rexCall, RelNode
input) {
+ if (rexCall.op.getKind() == SqlKind.TUMBLE) {
+ // construct a input ref over watermarked column.
+ // Before DESCRIPTOR is implemented, the second parameter of TUMBLE
+ // is a string, which is one of the column from input.
+ assert rexCall.getOperands().get(1) instanceof RexLiteral;
+ String watermarkedColumnName =
+ ((RexLiteral) rexCall.getOperands().get(1)).getValueAs(String.class);
+ int watermarkedColumnIndex = -1;
+ List<RexNode> schemaForwardInputRefs = new ArrayList<>();
+ for (int i = 0; i < input.getRowType().getFieldCount(); i++) {
+ if
(watermarkedColumnName.equals(input.getRowType().getFieldNames().get(i))) {
+ watermarkedColumnIndex = i;
+ }
+ schemaForwardInputRefs.add(builder.makeInputRef(input, i));
+ }
+ assert watermarkedColumnIndex > -1
+ && watermarkedColumnIndex < input.getRowType().getFieldCount();
+
+ List<Expression> translatedOperands =
translateList(schemaForwardInputRefs);
+
+ // convert the third parameter, which should be a literal for an
interval.
+ assert rexCall.getOperands().get(2) instanceof RexLiteral;
+ Expression intervalExpression = translate(rexCall.getOperands().get(2));
+
+ List<Expression> translatedOperandsForTumble = new ArrayList<>();
+
translatedOperandsForTumble.add(translatedOperands.get(watermarkedColumnIndex));
+ translatedOperandsForTumble.add(intervalExpression);
+ // compute the window_start
+ MethodNameImplementor windowStartMethod = new
MethodNameImplementor("tumbleWindowStart");
Review comment:
I found it was hard to add these to `RexImpTable` because one operator has
two implementor: window_start and window_end.
For TUMBLE and HOP, a workaround is only provide implementor for
window_start and later compute window_end by window_start + window_size.
However, it won't work for `SESSION`.
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