englefly commented on code in PR #64820: URL: https://github.com/apache/doris/pull/64820#discussion_r3524108100
########## fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/functions/scalar/Ipv4StringToNumOrDefault.java: ########## @@ -36,7 +37,7 @@ * scalar function ipv4_string_to_num_or_default */ public class Ipv4StringToNumOrDefault extends ScalarFunction Review Comment: review0705 ########## fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/functions/scalar/NullOrEmpty.java: ########## @@ -36,7 +37,7 @@ * ScalarFunction 'null_or_empty'. This class is generated by GenerateFunction. */ public class NullOrEmpty extends ScalarFunction Review Comment: review0705 ########## fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/NullToNonNullFunction.java: ########## @@ -0,0 +1,65 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +package org.apache.doris.nereids.trees.expressions; + +import org.apache.doris.nereids.trees.expressions.functions.AlwaysNotNullable; +import org.apache.doris.nereids.trees.expressions.functions.agg.AggregateFunction; + +/** + * Marker interface for expressions that can convert NULL input into a non-NULL output. + * + * For example: Coalesce(NULL, 2) → 2, Nvl(NULL, 0) → 0, NullOrEmpty(NULL) → true. + * + * This is significant for outer-join push-down safety: when an aggregate function contains + * a NullToNonNull expression wrapping a column from the nullable side of an outer join, + * the aggregation must NOT be pushed down. Null-extended rows (produced by the join for + * unmatched rows) have NULL for all nullable-side columns. The NullToNonNull expression + * would convert those NULLs to non-NULL values, and the pre-aggregation would miss those + * contributions because null-extended rows do not exist in the base table. + * + * <p>Note: {@link AlwaysNotNullable} expressions with input slots (e.g. Array, JsonArray, + * JsonObject, CreateStruct, CreateMap) are also blocked from being pushed to the nullable + * side of outer joins via a separate check in {@link #canConvertNullToNonNull(Expression)}. + */ +public interface NullToNonNullFunction { + + /** + * Check whether an expression can convert NULL input to non-NULL output. + * This covers both {@link NullToNonNullFunction} (e.g. Coalesce, Nvl, NullOrEmpty) + * and {@link AlwaysNotNullable} expressions with input slots (e.g. Array, JsonArray, Review Comment: review0705 -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
