Biasqo commented on code in PR #171: URL: https://github.com/apache/flink-connector-jdbc/pull/171#discussion_r4383724145
########## flink-connector-jdbc-clickhouse/src/main/java/org/apache/flink/connector/jdbc/clickhouse/database/dialect/ClickHouseDialect.java: ########## @@ -0,0 +1,139 @@ +/* + * 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.jdbc.clickhouse.database.dialect; + +import org.apache.flink.annotation.Internal; +import org.apache.flink.connector.jdbc.core.database.dialect.AbstractDialect; +import org.apache.flink.connector.jdbc.core.database.dialect.JdbcDialectConverter; +import org.apache.flink.table.types.logical.LogicalTypeRoot; +import org.apache.flink.table.types.logical.RowType; + +import java.util.Arrays; +import java.util.EnumSet; +import java.util.Optional; +import java.util.Set; +import java.util.stream.Collectors; + +import static java.lang.String.format; + +/** JDBC dialect for ClickHouse. */ +@Internal +public class ClickHouseDialect extends AbstractDialect { + + private static final long serialVersionUID = 1L; + + // Define MAX/MIN precision of TIMESTAMP type according to ClickHouse docs: + // https://clickhouse.com/docs/sql-reference/data-types/datetime64 + private static final int MAX_TIMESTAMP_PRECISION = 9; + private static final int MIN_TIMESTAMP_PRECISION = 0; + + // Define MAX/MIN precision of DECIMAL type according to ClickHouse docs: + // https://clickhouse.com/docs/sql-reference/data-types/decimal + private static final int MAX_DECIMAL_PRECISION = 76; + private static final int MIN_DECIMAL_PRECISION = 1; + + @Override + public JdbcDialectConverter getRowConverter(RowType rowType) { + return new ClickHouseDialectConverter(rowType); + } + + @Override + public String getLimitClause(long limit) { + return "LIMIT " + limit; + } + + @Override + public Optional<String> defaultDriverName() { + return Optional.of("com.clickhouse.jdbc.Driver"); + } + + @Override + public String dialectName() { + return "ClickHouse"; + } + + @Override + public String quoteIdentifier(String identifier) { + return identifier; + } + + // ClickHouse does not support Upsert statements + // Instead you can create a table with ReplacingMergeTree engine; + // https://clickhouse.com/docs/engines/table-engines/mergetree-family/replacingmergetree + @Override + public Optional<String> getUpsertStatement( + String tableName, String[] fieldNames, String[] uniqueKeyFields) { + return Optional.empty(); Review Comment: The `ALTER TABLE ... UPDATE mutation` is heavy but it guarantees no duplicates. Using a plain insert into Replacing*, deduplication happens in the background, so you have to use FINAL statement to read deduplicated values. The ClickHouse best practice is not to rely on PRIMARY KEY for deduplication - deduplication is driven by the ORDER BY sort key instead, and they do not have to be same, one can be a prefix of another. ########## flink-connector-jdbc-clickhouse/src/main/java/org/apache/flink/connector/jdbc/clickhouse/database/dialect/ClickHouseDialect.java: ########## @@ -0,0 +1,139 @@ +/* + * 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.jdbc.clickhouse.database.dialect; + +import org.apache.flink.annotation.Internal; +import org.apache.flink.connector.jdbc.core.database.dialect.AbstractDialect; +import org.apache.flink.connector.jdbc.core.database.dialect.JdbcDialectConverter; +import org.apache.flink.table.types.logical.LogicalTypeRoot; +import org.apache.flink.table.types.logical.RowType; + +import java.util.Arrays; +import java.util.EnumSet; +import java.util.Optional; +import java.util.Set; +import java.util.stream.Collectors; + +import static java.lang.String.format; + +/** JDBC dialect for ClickHouse. */ +@Internal +public class ClickHouseDialect extends AbstractDialect { + + private static final long serialVersionUID = 1L; + + // Define MAX/MIN precision of TIMESTAMP type according to ClickHouse docs: + // https://clickhouse.com/docs/sql-reference/data-types/datetime64 + private static final int MAX_TIMESTAMP_PRECISION = 9; + private static final int MIN_TIMESTAMP_PRECISION = 0; + + // Define MAX/MIN precision of DECIMAL type according to ClickHouse docs: + // https://clickhouse.com/docs/sql-reference/data-types/decimal + private static final int MAX_DECIMAL_PRECISION = 76; + private static final int MIN_DECIMAL_PRECISION = 1; + + @Override + public JdbcDialectConverter getRowConverter(RowType rowType) { + return new ClickHouseDialectConverter(rowType); + } + + @Override + public String getLimitClause(long limit) { + return "LIMIT " + limit; + } + + @Override + public Optional<String> defaultDriverName() { + return Optional.of("com.clickhouse.jdbc.Driver"); + } + + @Override + public String dialectName() { + return "ClickHouse"; + } + + @Override + public String quoteIdentifier(String identifier) { Review Comment: Done -- This is an automated message from the Apache Git Service. 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