zabetak commented on a change in pull request #1020: [CALCITE-2812] Add
algebraic operators to allow expressing recursive queries (Ruben Quesada Lopez)
URL: https://github.com/apache/calcite/pull/1020#discussion_r258433355
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File path: core/src/main/java/org/apache/calcite/tools/RelBuilder.java
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@@ -1616,6 +1619,58 @@ public RelBuilder minus(boolean all, int n) {
return setOp(all, SqlKind.EXCEPT, n);
}
+ /**
+ * Creates a {@link LogicalDeltaTableScan} of a delta work table (used to
accumulate results in
+ * recursive union operation), using as its row type the top of the stack.
+ * Returns this builder.
+ */
+ public RelBuilder deltaScan(String tableName) {
+ return this.deltaScan(tableName, this.peek().getRowType());
+ }
+
+ /**
+ * Creates a {@link LogicalDeltaTableScan} of a delta work table (used to
accumulate results in
+ * recursive union operation).
+ * Returns this builder.
+ * @param tableName table name
+ * @param rowType row type of the table
+ */
+ public RelBuilder deltaScan(String tableName, RelDataType rowType) {
+ RelOptTable table = RelOptTableImpl.create(
+ this.relOptSchema,
+ rowType,
+ Collections.singletonList(tableName),
+ null);
+ LogicalDeltaTableScan scan = LogicalDeltaTableScan.create(this.cluster,
table);
Review comment:
Regarding my previous comment of possibly removing LogicalDeltaTableScan
(replacing with LogicalTableScan) I was thinking that the RelOptTableImpl above
could be enhanced with adequate information which would make the need for a new
scan operator obsolete.
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