Jiabao-Sun commented on code in PR #17: URL: https://github.com/apache/flink-connector-mongodb/pull/17#discussion_r1374475234
########## flink-connector-mongodb/src/main/java/org/apache/flink/connector/mongodb/table/MongoFilterPushDownVisitor.java: ########## @@ -0,0 +1,251 @@ +/* + * 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.flink.connector.mongodb.table; + +import org.apache.flink.annotation.Experimental; +import org.apache.flink.table.expressions.CallExpression; +import org.apache.flink.table.expressions.Expression; +import org.apache.flink.table.expressions.ExpressionDefaultVisitor; +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.types.logical.LogicalType; + +import com.mongodb.client.model.Filters; +import org.bson.BsonBoolean; +import org.bson.BsonDateTime; +import org.bson.BsonDecimal128; +import org.bson.BsonDocument; +import org.bson.BsonDouble; +import org.bson.BsonInt32; +import org.bson.BsonInt64; +import org.bson.BsonNull; +import org.bson.BsonString; +import org.bson.BsonType; +import org.bson.BsonUndefined; +import org.bson.BsonValue; +import org.bson.conversions.Bson; +import org.bson.types.Decimal128; + +import java.math.BigDecimal; +import java.sql.Timestamp; +import java.time.Instant; +import java.time.LocalDateTime; +import java.util.List; +import java.util.Optional; + +/** + * Visitor that convert Expression to Bson filter. Return {@link Filters#empty()} if we cannot push + * down the filter. + */ +@Experimental +public class MongoFilterPushDownVisitor extends ExpressionDefaultVisitor<BsonValue> { + + public static final MongoFilterPushDownVisitor INSTANCE = new MongoFilterPushDownVisitor(); + + private MongoFilterPushDownVisitor() { + // Singleton instance. + } + + @Override + public BsonDocument visit(CallExpression call) { + Bson filter = Filters.empty(); + if (BuiltInFunctionDefinitions.EQUALS.equals(call.getFunctionDefinition())) { + filter = renderBinaryComparisonOperator("$eq", call.getResolvedChildren()); + } + if (BuiltInFunctionDefinitions.LESS_THAN.equals(call.getFunctionDefinition())) { + filter = renderBinaryComparisonOperator("$lt", call.getResolvedChildren()); + } + if (BuiltInFunctionDefinitions.LESS_THAN_OR_EQUAL.equals(call.getFunctionDefinition())) { + filter = renderBinaryComparisonOperator("$lte", call.getResolvedChildren()); + } + if (BuiltInFunctionDefinitions.GREATER_THAN.equals(call.getFunctionDefinition())) { + filter = renderBinaryComparisonOperator("$gt", call.getResolvedChildren()); + } + if (BuiltInFunctionDefinitions.GREATER_THAN_OR_EQUAL.equals(call.getFunctionDefinition())) { + filter = renderBinaryComparisonOperator("$gte", call.getResolvedChildren()); + } + if (BuiltInFunctionDefinitions.NOT_EQUALS.equals(call.getFunctionDefinition())) { + filter = renderBinaryComparisonOperator("$ne", call.getResolvedChildren()); + } + if (BuiltInFunctionDefinitions.IS_NULL.equals(call.getFunctionDefinition())) { + filter = + renderUnaryComparisonOperator( + "$eq", call.getResolvedChildren().get(0), BsonNull.VALUE); + } + if (BuiltInFunctionDefinitions.IS_NOT_NULL.equals(call.getFunctionDefinition())) { + filter = + renderUnaryComparisonOperator( + "$ne", call.getResolvedChildren().get(0), BsonNull.VALUE); + } + if (BuiltInFunctionDefinitions.OR.equals(call.getFunctionDefinition())) { + filter = renderLogicalOperator("$or", call.getResolvedChildren()); + } + if (BuiltInFunctionDefinitions.AND.equals(call.getFunctionDefinition())) { + filter = renderLogicalOperator("$and", call.getResolvedChildren()); + } + return filter.toBsonDocument(); + } + + private Bson renderBinaryComparisonOperator( + String operator, List<ResolvedExpression> expressions) { + Optional<FieldReferenceExpression> fieldReferenceExpr = Review Comment: MongoDB is more complicated in this situation, and it will cause full collection scanning, so it is temporarily regardless of the scene of Pushdown. https://stackoverflow.com/questions/4442453/mongodb-query-condition-on-comparing-2-fields -- This is an automated message from the Apache Git Service. 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