amaliujia commented on a change in pull request #1587: [CALCITE-3272] Support
TUMBLE as Table Valued Function including an enumerable implementation,
stream.iq and DESCRIPTOR
URL: https://github.com/apache/calcite/pull/1587#discussion_r358056660
##########
File path:
core/src/main/java/org/apache/calcite/adapter/enumerable/RexToLixTranslator.java
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@@ -937,6 +950,22 @@ public static Expression translateLiteral(
return list;
}
+ private List<Expression> translateTableFunctionCall(RexCall rexCall) {
+ if (rexCall.op.getKind() == SqlKind.TUMBLE) {
+ assert rexCall.getOperands().get(2) instanceof RexLiteral;
+ Expression intervalExpression = translate(rexCall.getOperands().get(2));
+ RexCall descriptor = (RexCall) rexCall.getOperands().get(1);
+ List<Expression> translatedOperandsForTumble = new ArrayList<>();
+ translatedOperandsForTumble.add(
+ Expressions.constant(((RexInputRef)
descriptor.getOperands().get(0)).getIndex()));
+ translatedOperandsForTumble.add(intervalExpression);
Review comment:
TUMBLE's signature is `TUMBLE(table, DESCRIPTOR(column_name), interval [,
time ])`, so it's supposed to only have one column name in `DESCRIPTOR` to
indicate watermarked event timestamp column.
It's good question that where TUMBLE's signature is validated such that we
guarantee`DESCRIPTOR` only has one column name and throw exception otherwise.
The answer is, seems to me that the best place is in SQL parser, in which it
will only create TUMBLE if `DESCRIPTOR` has one column. Or maybe the check
should happen within Operators by operand checkers or something similar.
`DESCRIPTOR` indeed is less mature at this moment. I am hoping it can be
improved gradually. I am planning to leave it as a future work.
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