Skip dimension slices when we have empty dimension restriction

src/hypertable_restrict_info.c

@@ -727,6 +727,46 @@ gather_restriction_dimension_vectors(const HypertableRestrictInfo *hri)
 			{
 				const DimensionRestrictInfoOpen *open = (const DimensionRestrictInfoOpen *) dri;
 
+				/*
+				 * Filter out contradictory dimension restrictions. If
+				 * lower_bound > upper_bound, no row can match, but some slices
+				 * still can, because we're checking the slice ends separately:
+				 * slice_start <= upper_bound <= lower_bound <= slice_end
+				 * The chunk will pass our hypertable expansion and will later
+				 * be excluded by the Postgres constraint exclusion that handles
+				 * contradictory clauses. This is extra work that we can easily
+				 * avoid now. Return early when the search intervals for slice
+				 * start and slice end do not overlap. These are given by the
+				 * upper/lower bound/strategy in the dimension restriction.
+				 */
+				if (open->upper_strategy != InvalidStrategy &&
+					open->lower_strategy != InvalidStrategy)
+				{
+					Assert(open->upper_strategy == BTLessEqualStrategyNumber ||
+						   open->upper_strategy == BTLessStrategyNumber);
+					Assert(open->lower_strategy == BTGreaterEqualStrategyNumber ||
+						   open->lower_strategy == BTGreaterStrategyNumber);
+
+					if (open->lower_bound > open->upper_bound)
+					{
+						/* No overlap. */
+						break;
+					}
+					else if (open->lower_bound == open->upper_bound)
+					{
+						/* Overlap if both intervals are inclusive. */
+						if (open->upper_strategy != BTLessEqualStrategyNumber ||
+							open->lower_strategy != BTGreaterEqualStrategyNumber)
+						{
+							break;
+						}
+					}
+					/* Overlap, proceed with finding the actual matching slices. */
+				}
+
+				/*
+				 * Find the slices matching the dimension restriction.
+				 */
 				ts_dimension_slice_scan_iterator_set_range(&it,
 														   open->base.dimension->fd.id,
 														   open->upper_strategy,