rdblue commented on a change in pull request #1893: URL: https://github.com/apache/iceberg/pull/1893#discussion_r557000212
########## File path: flink/src/main/java/org/apache/iceberg/flink/FlinkFilters.java ########## @@ -0,0 +1,266 @@ +/* + * 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.iceberg.flink; + +import java.time.Instant; +import java.time.LocalDate; +import java.time.LocalDateTime; +import java.time.LocalTime; +import java.util.List; +import java.util.Map; +import java.util.Optional; +import java.util.function.BiFunction; +import java.util.function.Function; +import java.util.regex.Matcher; +import java.util.regex.Pattern; +import org.apache.flink.api.java.tuple.Tuple2; +import org.apache.flink.table.expressions.CallExpression; +import org.apache.flink.table.expressions.FieldReferenceExpression; +import org.apache.flink.table.expressions.ResolvedExpression; +import org.apache.flink.table.expressions.ValueLiteralExpression; +import org.apache.flink.table.functions.BuiltInFunctionDefinitions; +import org.apache.flink.table.functions.FunctionDefinition; +import org.apache.iceberg.expressions.Expression; +import org.apache.iceberg.expressions.Expression.Operation; +import org.apache.iceberg.expressions.Expressions; +import org.apache.iceberg.relocated.com.google.common.collect.ImmutableMap; +import org.apache.iceberg.util.DateTimeUtil; +import org.apache.iceberg.util.NaNUtil; + +public class FlinkFilters { + private FlinkFilters() { + } + + private static final Pattern STARTS_WITH_PATTERN = Pattern.compile("([^%]+)%"); + + private static final Map<FunctionDefinition, Operation> FILTERS = ImmutableMap + .<FunctionDefinition, Operation>builder() + .put(BuiltInFunctionDefinitions.EQUALS, Operation.EQ) + .put(BuiltInFunctionDefinitions.NOT_EQUALS, Operation.NOT_EQ) + .put(BuiltInFunctionDefinitions.GREATER_THAN, Operation.GT) + .put(BuiltInFunctionDefinitions.GREATER_THAN_OR_EQUAL, Operation.GT_EQ) + .put(BuiltInFunctionDefinitions.LESS_THAN, Operation.LT) + .put(BuiltInFunctionDefinitions.LESS_THAN_OR_EQUAL, Operation.LT_EQ) + .put(BuiltInFunctionDefinitions.IS_NULL, Operation.IS_NULL) + .put(BuiltInFunctionDefinitions.IS_NOT_NULL, Operation.NOT_NULL) + .put(BuiltInFunctionDefinitions.AND, Operation.AND) + .put(BuiltInFunctionDefinitions.OR, Operation.OR) + .put(BuiltInFunctionDefinitions.NOT, Operation.NOT) + .put(BuiltInFunctionDefinitions.LIKE, Operation.STARTS_WITH) + .build(); + + /** + * Convert flink expression to iceberg expression. + * <p> + * the BETWEEN, NOT_BETWEEN, IN expression will be converted by flink automatically. the BETWEEN will be converted to + * (GT_EQ AND LT_EQ), the NOT_BETWEEN will be converted to (LT_EQ OR GT_EQ), the IN will be converted to OR, so we do + * not add the conversion here + * + * @param flinkExpression the flink expression + * @return the iceberg expression + */ + public static Optional<Expression> convert(org.apache.flink.table.expressions.Expression flinkExpression) { + if (!(flinkExpression instanceof CallExpression)) { + return Optional.empty(); + } + + CallExpression call = (CallExpression) flinkExpression; + Operation op = FILTERS.get(call.getFunctionDefinition()); + if (op != null) { + switch (op) { + case IS_NULL: + Optional<String> name = toReference(singleton(call, FieldReferenceExpression.class).orElse(null)); + return name.map(Expressions::isNull); + + case NOT_NULL: + Optional<String> nameNotNull = toReference(singleton(call, FieldReferenceExpression.class).orElse(null)); + return nameNotNull.map(Expressions::notNull); + + case LT: + return convertComparisonExpression(Expressions::lessThan, Expressions::greaterThan, call); + + case LT_EQ: + return convertComparisonExpression(Expressions::lessThanOrEqual, Expressions::greaterThanOrEqual, call); + + case GT: + return convertComparisonExpression(Expressions::greaterThan, Expressions::lessThan, call); + + case GT_EQ: + return convertComparisonExpression(Expressions::greaterThanOrEqual, Expressions::lessThanOrEqual, call); + + case EQ: + return handleNaN(Expressions::equal, Expressions::isNaN, call); + + case NOT_EQ: + return handleNaN(Expressions::notEqual, Expressions::notNaN, call); + + case NOT: + Optional<Expression> child = convert(singleton(call, CallExpression.class).orElse(null)); + return child.map(Expressions::not); + + case AND: + return convertLogicExpression(Expressions::and, call); + + case OR: + return convertLogicExpression(Expressions::or, call); + + case STARTS_WITH: + return convertLike(call); + } + } + + return Optional.empty(); + } + + private static <T extends ResolvedExpression> Optional<T> singleton(CallExpression call, + Class<T> expectedChildClass) { + List<ResolvedExpression> children = call.getResolvedChildren(); + if (children.size() != 1) { + return Optional.empty(); + } + + ResolvedExpression child = children.get(0); + if (!expectedChildClass.isInstance(child)) { + return Optional.empty(); + } + + return Optional.of(expectedChildClass.cast(child)); + } + + private static Optional<Expression> convertLike(CallExpression call) { + Tuple2<String, Object> tuple2 = parseFieldAndLiteral(call); + if (tuple2 == null) { + return Optional.empty(); + } + + String pattern = tuple2.f1.toString(); + Matcher matcher = STARTS_WITH_PATTERN.matcher(pattern); + + // exclude special char of LIKE + // '_' is the wildcard of the SQL LIKE + if (!pattern.contains("_") && matcher.matches()) { + return Optional.of(Expressions.startsWith(tuple2.f0, matcher.group(1))); + } + + return Optional.empty(); + } + + private static Optional<Expression> convertLogicExpression(BiFunction<Expression, Expression, Expression> function, + CallExpression call) { + List<ResolvedExpression> args = call.getResolvedChildren(); + Optional<Expression> left = convert(args.get(0)); + Optional<Expression> right = convert(args.get(1)); + if (left.isPresent() && right.isPresent()) { + return Optional.of(function.apply(left.get(), right.get())); + } + + return Optional.empty(); + } + + private static Optional<Expression> convertComparisonExpression( + BiFunction<String, Object, Expression> function, BiFunction<String, Object, Expression> reversedFunction, + CallExpression call) { + Tuple2<String, Object> tuple2 = parseFieldAndLiteral(call); + if (tuple2 != null) { + if (literalOnRight(call.getResolvedChildren())) { + return Optional.of(function.apply(tuple2.f0, tuple2.f1)); + } else { + return Optional.of(reversedFunction.apply(tuple2.f0, tuple2.f1)); + } + } else { + return Optional.empty(); + } + } + + private static Optional<String> toReference(org.apache.flink.table.expressions.Expression expression) { + return expression instanceof FieldReferenceExpression ? + Optional.of(((FieldReferenceExpression) expression).getName()) : + Optional.empty(); + } + + private static Optional<Object> toLiteral(org.apache.flink.table.expressions.Expression expression) { + // Not support null literal + return expression instanceof ValueLiteralExpression ? + convertLiteral((ValueLiteralExpression) expression) : + Optional.empty(); + } + + private static Optional<Expression> handleNaN(BiFunction<String, Object, Expression> function, + Function<String, Expression> functionNaN, + CallExpression call) { + Tuple2<String, Object> tuple2 = parseFieldAndLiteral(call); + if (tuple2 == null) { + return Optional.empty(); + } + + String name = tuple2.f0; + Object value = tuple2.f1; + + if (NaNUtil.isNaN(value)) { + return Optional.of(functionNaN.apply(name)); + } else { + return Optional.of(function.apply(name, value)); + } + } + + private static Optional<Object> convertLiteral(ValueLiteralExpression expression) { + Optional<?> value = expression.getValueAs(expression.getOutputDataType().getLogicalType().getDefaultConversion()); + return value.map(o -> { + if (o instanceof LocalDateTime) { + return DateTimeUtil.microsFromTimestamp((LocalDateTime) o); + } else if (o instanceof Instant) { + return DateTimeUtil.microsFromInstant((Instant) o); + } else if (o instanceof LocalTime) { + return DateTimeUtil.microsFromTime((LocalTime) o); + } else if (o instanceof LocalDate) { + return DateTimeUtil.daysFromDate((LocalDate) o); + } + + return o; + }); + } + + private static boolean literalOnRight(List<ResolvedExpression> args) { + return args.get(0) instanceof FieldReferenceExpression && args.get(1) instanceof ValueLiteralExpression; + } + + private static Tuple2<String, Object> parseFieldAndLiteral(CallExpression call) { Review comment: I think that this class can be cleaned up by rewriting this method. I think this was intended to make reuse easier, but rewriting this allows removing several methods (`literalOnRight`, `convertComparisonExpression`, `handleNaN`, `toReference`, and `toLiteral`), gets rid of the strange method contract where `Tuple2` and `null` are used, and also ensures that `instanceof` checks are done in just one place, rather than with multiple calls to `literalOnRight`. Here's what I rewrote it to: ```java private static Optional<Expression> convertFieldAndLiteral(BiFunction<String, Object, Expression> expr, CallExpression call) { return convertFieldAndLiteral(expr, expr, call); } private static Optional<Expression> convertFieldAndLiteral( BiFunction<String, Object, Expression> convertLR, BiFunction<String, Object, Expression> convertRL, CallExpression call) { List<ResolvedExpression> args = call.getResolvedChildren(); if (args.size() != 2) { return Optional.empty(); } org.apache.flink.table.expressions.Expression left = args.get(0); org.apache.flink.table.expressions.Expression right = args.get(1); if (left instanceof FieldReferenceExpression && right instanceof ValueLiteralExpression) { String name = ((FieldReferenceExpression) left).getName(); Object lit = convertLiteral((ValueLiteralExpression) right); return Optional.of(convertLR.apply(name, lit)); } else if (left instanceof ValueLiteralExpression && right instanceof FieldReferenceExpression) { Object lit = convertLiteral((ValueLiteralExpression) left); String name = ((FieldReferenceExpression) right).getName(); return Optional.of(convertRL.apply(name, lit)); } return Optional.empty(); } ``` The comparison cases in the `switch` statement can then call this directly: ```java switch (op) { case LT: return convertFieldAndLiteral(Expressions::lessThan, Expressions::greaterThan, call); case LT_EQ: return convertFieldAndLiteral(Expressions::lessThanOrEqual, Expressions::greaterThanOrEqual, call); case GT: return convertFieldAndLiteral(Expressions::greaterThan, Expressions::lessThan, call); case GT_EQ: return convertFieldAndLiteral(Expressions::greaterThanOrEqual, Expressions::lessThanOrEqual, call); case EQ: return convertFieldAndLiteral((ref, lit) -> { if (NaNUtil.isNaN(lit)) { return Expressions.isNaN(ref); } else { return Expressions.equal(ref, lit); } }, call); case NOT_EQ: return convertFieldAndLiteral((ref, lit) -> { if (NaNUtil.isNaN(lit)) { return Expressions.notNaN(ref); } else { return Expressions.notEqual(ref, lit); } }, call); ``` The only problem is that `convertLike` can't call this. But that's okay because I don't think the reversed form of `LIKE` is actually supported anyway (`"a%" LIKE col` is not allowed, right?). So I also rewrote `convertLike`: ```java private static Optional<Expression> convertLike(CallExpression call) { List<ResolvedExpression> args = call.getResolvedChildren(); if (args.size() != 2) { return Optional.empty(); } org.apache.flink.table.expressions.Expression left = args.get(0); org.apache.flink.table.expressions.Expression right = args.get(1); if (left instanceof FieldReferenceExpression && right instanceof ValueLiteralExpression) { String name = ((FieldReferenceExpression) left).getName(); return convertLiteral((ValueLiteralExpression) right).flatMap(lit -> { if (lit instanceof String) { String pattern = (String) lit; Matcher matcher = STARTS_WITH_PATTERN.matcher(pattern); // exclude special char of LIKE // '_' is the wildcard of the SQL LIKE if (!pattern.contains("_") && matcher.matches()) { return Optional.of(Expressions.startsWith(name, matcher.group(1))); } } return Optional.empty(); }); } return Optional.empty(); } ``` ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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