xiedeyantu commented on code in PR #5004:
URL: https://github.com/apache/calcite/pull/5004#discussion_r3446435489
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core/src/main/java/org/apache/calcite/adapter/enumerable/EnumerableLimit.java:
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@@ -133,4 +141,147 @@ static Expression getExpression(RexNode rexNode) {
return Expressions.constant(RexLiteral.intValue(rexNode));
}
}
+
+ static Expression getExpressionForFetch(RexNode rexNode,
+ EnumerableRelImplementor implementor, BlockBuilder builder) {
+ if (rexNode instanceof RexDynamicParam) {
+ final RexDynamicParam param = (RexDynamicParam) rexNode;
+ return Expressions.call(EnumerableLimit.class, "toIntFetch",
+ Expressions.convert_(
+ Expressions.call(DataContext.ROOT,
+ BuiltInMethod.DATA_CONTEXT_GET.method,
+ Expressions.constant("?" + param.getIndex())),
+ Number.class));
+ } else if (rexNode instanceof RexLiteral) {
+ return Expressions.constant(
+ toIntFetch(((RexLiteral) rexNode).getValueAs(Number.class)));
+ } else {
+ final Expression expression =
+ RexToLixTranslator.forAggregation(implementor.getTypeFactory(),
+ builder, null, implementor.getConformance())
+ .translate(rexNode);
+ return Expressions.call(EnumerableLimit.class, "toIntFetch",
+ Expressions.convert_(Expressions.box(expression), Number.class));
+ }
+ }
+
+ /** Converts a FETCH expression result to the range supported by Enumerable.
*/
+ public static int toIntFetch(@Nullable Number value) {
+ final BigDecimal decimal = validateFetchValue(value);
+ final int result;
+ try {
+ result = decimal.intValueExact();
+ } catch (ArithmeticException e) {
+ throw new IllegalArgumentException("FETCH value " + value
+ + " is out of range; expected a value between 0 and "
+ + Integer.MAX_VALUE, e);
+ }
+ if (result < 0) {
+ throw new IllegalArgumentException("FETCH value " + value
+ + " is out of range; expected a value between 0 and "
+ + Integer.MAX_VALUE);
+ }
+ return result;
+ }
+
+ /** Converts a FETCH expression result to the range supported by a long. */
+ public static long toLongFetch(@Nullable Number value) {
+ final BigDecimal decimal = validateFetchValue(value);
+ final long result;
+ try {
+ result = decimal.longValueExact();
+ } catch (ArithmeticException e) {
+ throw new IllegalArgumentException("FETCH value " + value
Review Comment:
In Calcite, the LIMIT and OFFSET values are not restricted to the LONG
type; they can be arbitrarily large. As this link, we will use BigDecimal. Is
the restriction to the long type here due to issues with Enumerable execution?
The `int` above has the same issue.
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