voonhous commented on code in PR #17599: URL: https://github.com/apache/hudi/pull/17599#discussion_r2650139460
########## hudi-common/src/main/java/org/apache/hudi/common/schema/HoodieSchemaComparatorForSchemaEvolution.java: ########## @@ -0,0 +1,375 @@ +/* + * 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.hudi.common.schema; + +import java.util.List; +import java.util.Set; +import java.util.stream.Collectors; + +/** + * Defines equality comparison rules for HoodieSchema schemas for schema evolution purposes. + * + * <p>This class provides schema comparison logic that focuses only on attributes that affect + * data readers/writers, ignoring metadata like documentation, namespace, and aliases which + * don't impact schema evolution compatibility.</p> + * + * <h2>Common Rules Across All Types</h2> + * Included in equality check: + * <ul> + * <li>Name/identifier</li> + * <li>Type including primitive type, complex type (see below), and logical type</li> + * </ul> + * Excluded from equality check: + * <ul> + * <li>Namespace</li> + * <li>Documentation</li> + * <li>Aliases</li> + * <li>Custom properties</li> + * </ul> + * + * <h2>Type-Specific Rules</h2> + * + * <h3>Record</h3> + * Included: + * <ul> + * <li>Field names</li> + * <li>Field types</li> + * <li>Field order attribute</li> + * <li>Default values</li> + * </ul> + * Excluded: + * <ul> + * <li>Field documentation</li> + * <li>Field aliases</li> + * </ul> + * + * <h3>Enum</h3> + * Included: + * <ul> + * <li>Name</li> + * <li>Symbol order</li> + * <li>Symbol value</li> + * </ul> + * Excluded: + * <ul> + * <li>Custom properties</li> + * </ul> + * + * <h3>Array</h3> + * Included: + * <ul> + * <li>Items schema</li> + * </ul> + * Excluded: + * <ul> + * <li>Documentation</li> + * <li>Custom properties</li> + * </ul> + * + * <h3>Map</h3> + * Included: + * <ul> + * <li>Values schema</li> + * </ul> + * Excluded: + * <ul> + * <li>Documentation</li> + * <li>Custom properties</li> + * </ul> + * + * <h3>Fixed</h3> + * Included: + * <ul> + * <li>Size</li> + * <li>Name</li> + * </ul> + * Excluded: + * <ul> + * <li>Namespace</li> + * <li>Aliases</li> + * </ul> + * + * <h3>Union</h3> + * Included: + * <ul> + * <li>Member types</li> + * </ul> + * Excluded: + * <ul> + * <li>Member order</li> + * </ul> + * + * <h3>Logical Types</h3> + * Included: + * <ul> + * <li>Logical type name (via schema subclass)</li> + * <li>Underlying primitive type</li> + * <li>Decimal precision/scale (if applicable)</li> + * <li>Timestamp/Time precision (if applicable)</li> + * </ul> + * Excluded: + * <ul> + * <li>Documentation</li> + * <li>Custom properties</li> + * </ul> + */ +public class HoodieSchemaComparatorForSchemaEvolution { + + protected HoodieSchemaComparatorForSchemaEvolution() { + } + + private static final HoodieSchemaComparatorForSchemaEvolution VALIDATOR = new HoodieSchemaComparatorForSchemaEvolution(); + + public static boolean schemaEquals(HoodieSchema s1, HoodieSchema s2) { + return VALIDATOR.schemaEqualsInternal(s1, s2); + } + + protected boolean schemaEqualsInternal(HoodieSchema s1, HoodieSchema s2) { + if (s1 == s2) { + return true; + } + if (s1 == null || s2 == null) { + return false; + } + if (s1.getType() != s2.getType()) { + return false; + } + + switch (s1.getType()) { + case RECORD: + return recordSchemaEquals(s1, s2); + case ENUM: + return enumSchemaEquals(s1, s2); + case ARRAY: + return arraySchemaEquals(s1, s2); + case MAP: + return mapSchemaEquals(s1, s2); + case FIXED: + return fixedSchemaEquals(s1, s2); + case UNION: + return unionSchemaEquals(s1, s2); + case STRING: + case BYTES: + case INT: + case LONG: + case FLOAT: + case DOUBLE: + case BOOLEAN: + case NULL: + case DECIMAL: + case TIME: + case TIMESTAMP: + case DATE: + case UUID: + return primitiveSchemaEquals(s1, s2); + default: + throw new IllegalArgumentException("Unknown schema type: " + s1.getType()); + } + } + + protected boolean validateRecord(HoodieSchema s1, HoodieSchema s2) { + if (s1.isError() != s2.isError()) { + return false; + } + + return logicalTypeSchemaEquals(s1, s2); + } + + private boolean recordSchemaEquals(HoodieSchema s1, HoodieSchema s2) { + if (!validateRecord(s1, s2)) { + return false; + } + + List<HoodieSchemaField> fields1 = s1.getFields(); + List<HoodieSchemaField> fields2 = s2.getFields(); + + if (fields1.size() != fields2.size()) { + return false; + } + + for (int i = 0; i < fields1.size(); i++) { + if (!fieldEquals(fields1.get(i), fields2.get(i))) { + return false; + } + } + return true; + } + + protected boolean validateField(HoodieSchemaField f1, HoodieSchemaField f2) { + if (!f1.name().equals(f2.name())) { + return false; + } + + if (f1.order() != f2.order()) { + return false; + } + + // Check if both have default values + if (f1.hasDefaultValue() != f2.hasDefaultValue()) { + return false; + } + + // If both have default values, they must be equal + if (f1.hasDefaultValue() && !f1.defaultVal().get().equals(f2.defaultVal().get())) { + return false; + } + + return true; + } + + private boolean fieldEquals(HoodieSchemaField f1, HoodieSchemaField f2) { + if (!validateField(f1, f2)) { + return false; + } + + return schemaEqualsInternal(f1.schema(), f2.schema()); + } + + protected boolean enumSchemaEquals(HoodieSchema s1, HoodieSchema s2) { + // Check name equality first + if (!s1.getName().equals(s2.getName())) { + return false; + } + + List<String> symbols1 = s1.getEnumSymbols(); + List<String> symbols2 = s2.getEnumSymbols(); + + // Quick size check before creating sets + if (symbols1.size() != symbols2.size()) { + return false; + } + + return symbols1.equals(symbols2); + } + + protected boolean unionSchemaEquals(HoodieSchema s1, HoodieSchema s2) { + List<HoodieSchema> types1 = s1.getTypes(); + List<HoodieSchema> types2 = s2.getTypes(); + + if (types1.size() != types2.size()) { + return false; + } + + // Create sets of effectively equal types + Set<SchemaWrapper> set1 = types1.stream().map(SchemaWrapper::new).collect(Collectors.toSet()); + Set<SchemaWrapper> set2 = types2.stream().map(SchemaWrapper::new).collect(Collectors.toSet()); + + // Compare sets instead of ordered lists + return set1.equals(set2); + } + + private boolean arraySchemaEquals(HoodieSchema s1, HoodieSchema s2) { + return schemaEqualsInternal(s1.getElementType(), s2.getElementType()); + } + + private boolean mapSchemaEquals(HoodieSchema s1, HoodieSchema s2) { + return schemaEqualsInternal(s1.getValueType(), s2.getValueType()); + } + + protected boolean validateFixed(HoodieSchema s1, HoodieSchema s2) { + return s1.getName().equals(s2.getName()) && s1.getFixedSize() == s2.getFixedSize(); + } + + private boolean fixedSchemaEquals(HoodieSchema s1, HoodieSchema s2) { + if (!validateFixed(s1, s2)) { + return false; + } + return logicalTypeSchemaEquals(s1, s2); + } + + private static boolean primitiveSchemaEquals(HoodieSchema s1, HoodieSchema s2) { + // For primitive types, just check logical type + return logicalTypeSchemaEquals(s1, s2); + } + + private static boolean logicalTypeSchemaEquals(HoodieSchema s1, HoodieSchema s2) { + // Check if both schemas are of the same logical type class + boolean s1IsDecimal = s1.getType() == HoodieSchemaType.DECIMAL; + boolean s2IsDecimal = s2.getType() == HoodieSchemaType.DECIMAL; + boolean s1IsTimestamp = s1.getType() == HoodieSchemaType.TIMESTAMP; + boolean s2IsTimestamp = s2.getType() == HoodieSchemaType.TIMESTAMP; + boolean s1IsTime = s1.getType() == HoodieSchemaType.TIME; + boolean s2IsTime = s2.getType() == HoodieSchemaType.TIME; + + // If one is a logical type and the other isn't, they're not equal + if (s1IsDecimal != s2IsDecimal || s1IsTimestamp != s2IsTimestamp || s1IsTime != s2IsTime) { + return false; + } + + // If both are decimals, compare precision, scale, and underlying type (FIXED vs BYTES) + if (s1IsDecimal) { + HoodieSchema.Decimal d1 = (HoodieSchema.Decimal) s1; + HoodieSchema.Decimal d2 = (HoodieSchema.Decimal) s2; + // Check if both use same underlying representation (FIXED vs BYTES) Review Comment: Sorry, i pushed to the changes to wrong branch... 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