thomasrebele commented on code in PR #6293:
URL: https://github.com/apache/hive/pull/6293#discussion_r2910085830
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ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/stats/FilterSelectivityEstimator.java:
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@@ -184,91 +189,383 @@ public Double visitCall(RexCall call) {
return selectivity;
}
+ /**
+ * Return whether the expression is a removable cast based on stats and type
bounds.
+ *
+ * <p>
+ * In Hive, if a value cannot be represented by the cast, the result of the
cast is NULL,
+ * and therefore cannot fulfill the predicate. So the possible range of the
values
+ * is limited by the range of possible values of the type.
+ * </p>
+ *
+ * @param exp the expression to check
+ * @param tableScan the table that provides the statistics
+ * @return true if the expression is a removable cast, false otherwise
+ */
+ private boolean isRemovableCast(RexNode exp, HiveTableScan tableScan) {
+ if(SqlKind.CAST != exp.getKind()) {
+ return false;
+ }
+ RexCall cast = (RexCall) exp;
+ RexNode op0 = cast.getOperands().getFirst();
+ if (!(op0 instanceof RexInputRef)) {
+ return false;
+ }
+ int index = ((RexInputRef) op0).getIndex();
+ final List<ColStatistics> colStats =
tableScan.getColStat(Collections.singletonList(index));
+ if (colStats.isEmpty()) {
+ return false;
+ }
+
+ SqlTypeName sourceType = op0.getType().getSqlTypeName();
+ SqlTypeName targetType = cast.getType().getSqlTypeName();
+
+ switch (sourceType) {
+ case TINYINT, SMALLINT, INTEGER, BIGINT:
+ switch (targetType) {// additional checks are needed
+ case TINYINT, SMALLINT, INTEGER, BIGINT:
+ return isRemovableIntegerCast(cast, op0, colStats);
+ case FLOAT, DOUBLE, DECIMAL:
+ return true;
+ default:
+ return false;
Review Comment:
The return statements are necessary to prevent a fall-through to the next
case of the outer switch.
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