morrySnow commented on code in PR #11802: URL: https://github.com/apache/doris/pull/11802#discussion_r949119354
########## fe/fe-core/src/main/java/org/apache/doris/nereids/rules/expression/rewrite/rules/TypeCoercion.java: ########## @@ -0,0 +1,394 @@ +// 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.rules.expression.rewrite.rules; + +import org.apache.doris.nereids.annotation.Developing; +import org.apache.doris.nereids.rules.expression.rewrite.AbstractExpressionRewriteRule; +import org.apache.doris.nereids.rules.expression.rewrite.ExpressionRewriteContext; +import org.apache.doris.nereids.trees.expressions.BinaryOperator; +import org.apache.doris.nereids.trees.expressions.CaseWhen; +import org.apache.doris.nereids.trees.expressions.Cast; +import org.apache.doris.nereids.trees.expressions.Expression; +import org.apache.doris.nereids.trees.expressions.InPredicate; +import org.apache.doris.nereids.trees.expressions.typecoercion.ImplicitCastInputTypes; +import org.apache.doris.nereids.types.BigIntType; +import org.apache.doris.nereids.types.BooleanType; +import org.apache.doris.nereids.types.DataType; +import org.apache.doris.nereids.types.DecimalType; +import org.apache.doris.nereids.types.DoubleType; +import org.apache.doris.nereids.types.FloatType; +import org.apache.doris.nereids.types.IntegerType; +import org.apache.doris.nereids.types.LargeIntType; +import org.apache.doris.nereids.types.NullType; +import org.apache.doris.nereids.types.NumericType; +import org.apache.doris.nereids.types.PrimitiveType; +import org.apache.doris.nereids.types.SmallIntType; +import org.apache.doris.nereids.types.StringType; +import org.apache.doris.nereids.types.TinyIntType; +import org.apache.doris.nereids.types.VarcharType; +import org.apache.doris.nereids.types.coercion.AbstractDataType; +import org.apache.doris.nereids.types.coercion.CharacterType; +import org.apache.doris.nereids.types.coercion.FractionalType; +import org.apache.doris.nereids.types.coercion.IntegralType; +import org.apache.doris.nereids.types.coercion.TypeCollection; + +import com.google.common.collect.ImmutableList; +import com.google.common.collect.Lists; +import com.google.common.collect.Sets; + +import java.util.List; +import java.util.Map; +import java.util.Optional; +import java.util.concurrent.atomic.AtomicInteger; +import java.util.function.Supplier; +import java.util.stream.Collectors; +import java.util.stream.Stream; + +/** + * a rule to add implicit cast for expressions. + */ +@Developing +public class TypeCoercion extends AbstractExpressionRewriteRule { + + public static final TypeCoercion INSTANCE = new TypeCoercion(); + + public static final List<DataType> NUMERIC_PRECEDENCE = ImmutableList.of( + DoubleType.INSTANCE, + LargeIntType.INSTANCE, + FloatType.INSTANCE, + BigIntType.INSTANCE, + IntegerType.INSTANCE, + SmallIntType.INSTANCE, + TinyIntType.INSTANCE + ); + + @Override + public Expression rewrite(Expression expr, ExpressionRewriteContext ctx) { + if (expr instanceof ImplicitCastInputTypes) { + return visitImplicitCastInputTypes(expr, ctx); + } else { + return super.rewrite(expr, ctx); + } + } + + // TODO: add other expression visitor function to do type coercion if necessary. + + @Override + public Expression visitBinaryOperator(BinaryOperator binaryOperator, ExpressionRewriteContext context) { + Expression left = binaryOperator.left(); + Expression right = binaryOperator.right(); + if (!canHandleTypeCoercion(left.getDataType(), right.getDataType())) { + return binaryOperator; + } + return findTightestCommonType(left.getDataType(), right.getDataType()) + .map(commonType -> { + if (binaryOperator.inputType().acceptsType(commonType) && ( + !left.getDataType().equals(commonType) || !right.getDataType().equals(commonType))) { + Expression newLeft = left; + Expression newRight = right; + if (!left.getDataType().equals(commonType)) { + newLeft = new Cast(left, commonType); + } + if (!right.getDataType().equals(commonType)) { + newRight = new Cast(right, commonType); + } + return binaryOperator.withChildren(newLeft, newRight); + } else { + return binaryOperator; + } + }) + .orElse(binaryOperator); + } + + @Override + public Expression visitCaseWhen(CaseWhen caseWhen, ExpressionRewriteContext context) { + List<DataType> dataTypesForCoercion = caseWhen.dataTypesForCoercion(); + if (dataTypesForCoercion.size() <= 1) { + return caseWhen; + } + DataType first = dataTypesForCoercion.get(0); + if (dataTypesForCoercion.stream().allMatch(dataType -> dataType.equals(first))) { + return caseWhen; + } + Optional<DataType> optionalCommonType = findWiderCommonType(dataTypesForCoercion); + return optionalCommonType + .map(commonType -> { + List<Expression> newChildren + = caseWhen.getWhenClauses().stream() + .map(wc -> wc.withChildren(wc.getOperand(), + castIfNotSameType(wc.getResult(), commonType))) + .collect(Collectors.toList()); + caseWhen.getDefaultValue() + .map(dv -> castIfNotSameType(dv, commonType)) + .ifPresent(newChildren::add); + return caseWhen.withChildren(newChildren); + }) + .orElse(caseWhen); + } + + @Override + public Expression visitInPredicate(InPredicate inPredicate, ExpressionRewriteContext context) { + if (inPredicate.getOptions().stream().map(Expression::getDataType) + .allMatch(dt -> dt.equals(inPredicate.getCompareExpr().getDataType()))) { + return inPredicate; + } + Optional<DataType> optionalCommonType = findWiderCommonType(inPredicate.children() + .stream().map(Expression::getDataType).collect(Collectors.toList())); + + return optionalCommonType + .map(commonType -> { + List<Expression> newChildren = inPredicate.children().stream() + .map(e -> castIfNotSameType(e, commonType)) + .collect(Collectors.toList()); + return inPredicate.withChildren(newChildren); + }) + .orElse(inPredicate); + } + + /** + * Do implicit cast for expression's children. + */ + private Expression visitImplicitCastInputTypes(Expression expr, ExpressionRewriteContext ctx) { + ImplicitCastInputTypes implicitCastInputTypes = (ImplicitCastInputTypes) expr; + List<Expression> newChildren = Lists.newArrayListWithCapacity(expr.arity()); + AtomicInteger changed = new AtomicInteger(0); + for (int i = 0; i < implicitCastInputTypes.expectedInputTypes().size(); i++) { + newChildren.add(implicitCast(expr.child(i), implicitCastInputTypes.expectedInputTypes().get(i), ctx) + .map(e -> { + changed.incrementAndGet(); + return e; + }) + .orElse(expr.child(0)) + ); + } + if (changed.get() != 0) { + return expr.withChildren(newChildren); + } else { + return expr; + } + } + + /** + * Return Optional.empty() if we cannot do or do not need to do implicit cast. + */ + @Developing + private Optional<Expression> implicitCast(Expression input, AbstractDataType expected, + ExpressionRewriteContext ctx) { + Expression rewrittenInput = rewrite(input, ctx); + Optional<DataType> castDataType = implicitCast(rewrittenInput.getDataType(), expected); + if (castDataType.isPresent() && !castDataType.get().equals(rewrittenInput.getDataType())) { + return Optional.of(new Cast(rewrittenInput, castDataType.get())); + } else { + // TODO: there maybe has performance problem, we need use ctx to save whether children is changed. + if (rewrittenInput.equals(input)) { + return Optional.empty(); + } else { + return Optional.of(rewrittenInput); + } + } + } + + /** + * Return Optional.empty() if cannot do implicit cast. + * TODO: datetime and date type + */ + @Developing + private Optional<DataType> implicitCast(DataType input, AbstractDataType expected) { + DataType returnType = null; + if (expected.acceptsType(input)) { + // If the expected type is already a parent of the input type, no need to cast. + return Optional.of(input); + } + if (expected instanceof TypeCollection) { + TypeCollection typeCollection = (TypeCollection) expected; + // use origin datatype first. use implicit cast instead if origin type cannot be accepted. + return Stream.<Supplier<Optional<DataType>>>of( + () -> typeCollection.getTypes().stream() + .filter(e -> e.acceptsType(input)) + .map(e -> input) + .findFirst(), + () -> typeCollection.getTypes().stream() + .map(e -> implicitCast(input, e)) + .filter(Optional::isPresent) + .map(Optional::get) + .findFirst()) + .map(Supplier::get) + .filter(Optional::isPresent) + .map(Optional::get) + .findFirst(); + } + if (input.isNullType()) { + // Cast null type (usually from null literals) into target types + returnType = expected.defaultConcreteType(); + } else if (input.isNumericType() && expected instanceof DecimalType) { + // If input is a numeric type but not decimal, and we expect a decimal type, + // cast the input to decimal. + returnType = DecimalType.forType(input); + } else if (input.isNumericType() && expected instanceof NumericType) { + // For any other numeric types, implicitly cast to each other, e.g. bigint -> int, int -> bigint + returnType = (DataType) expected; + } else if (input.isStringType()) { + if (expected instanceof DecimalType) { + returnType = DecimalType.SYSTEM_DEFAULT; + } else if (expected instanceof NumericType) { + returnType = expected.defaultConcreteType(); + } + } else if (input.isPrimitive() && !input.isStringType() && expected instanceof CharacterType) { + returnType = StringType.INSTANCE; + } + + // could not do implicit cast, just return null. Throw exception in check analysis. + return Optional.ofNullable(returnType); + } + + private boolean canHandleTypeCoercion(DataType leftType, DataType rightType) { + if (leftType instanceof DecimalType && rightType instanceof NullType) { + return true; + } + if (leftType instanceof NullType && rightType instanceof DecimalType) { + return true; + } + if (!(leftType instanceof DecimalType) && !(rightType instanceof DecimalType) && !leftType.equals(rightType)) { + return true; + } + return false; + } + + // TODO: compatible with origin planner and BE + // TODO: when add new type, add it to here + @Developing + private Optional<DataType> findTightestCommonType(DataType left, DataType right) { Review Comment: yes, will add it in next PR about type coercion -- 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: commits-unsubscr...@doris.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@doris.apache.org For additional commands, e-mail: commits-h...@doris.apache.org
