julianhyde commented on a change in pull request #1102: [CALCITE-1515]
RelBuilder supports creating TableFunctionScan
URL: https://github.com/apache/calcite/pull/1102#discussion_r265401364
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File path: core/src/main/java/org/apache/calcite/tools/RelBuilder.java
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@@ -1045,6 +1053,66 @@ public RelBuilder snapshot(RexNode period) {
return this;
}
+
+ /**
+ * Gets column mappings of the operator.
+ *
+ * @param op operator instance
+ * @return column mappings associated with this function
+ */
+ private Set<RelColumnMapping> getColumnMappings(SqlOperator op) {
+ SqlReturnTypeInference inference = op.getReturnTypeInference();
+ if (inference instanceof TableFunctionReturnTypeInference) {
+ return ((TableFunctionReturnTypeInference)
inference).getColumnMappings();
+ } else {
+ return null;
+ }
+ }
+
+ /**
+ * Create a RexCall to the CURSOR function by ordinal.
+ *
+ * @param ordinal the reference to the relational input
+ * @return RexCall to CURSOR function
+ */
+ public RexNode cursor(int ordinal) {
+ return getRexBuilder().makeCall(SqlStdOperatorTable.CURSOR, getRexBuilder()
+ .makeInputRef(peek(stack.size() - ordinal - 1).getRowType(), ordinal));
+ }
+
Review comment:
Currently the cursor function accesses the `ordinal`th element from the top
of the stack. So, if we create a table function with two inputs, the left input
will be cursor(1) and the right input will be cursor(0).
But we actually want them to be the other way around.
I suggest that you add an `inputCount` parameter (see: `field(inputCount,
inputOrdinal, fieldOrdinal)`). Thus the left input would be `cursor(2, 0)`, and
the right input would be `cursor(2, 1)`.
By the way, it is correct to call `peek` here. But `functionScan` should
call pop for each input.
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