paul-rogers commented on a change in pull request #2290: URL: https://github.com/apache/drill/pull/2290#discussion_r692559422
########## File path: contrib/storage-jdbc/src/main/java/org/apache/drill/exec/store/jdbc/JdbcSqlGenerator.java ########## @@ -0,0 +1,47 @@ +/* + * 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.drill.exec.store.jdbc; + +import org.apache.calcite.adapter.java.JavaTypeFactory; +import org.apache.calcite.adapter.jdbc.JdbcImplementor; +import org.apache.calcite.plan.RelOptCluster; +import org.apache.calcite.rel.RelNode; +import org.apache.calcite.sql.SqlDialect; +import org.apache.drill.exec.store.SubsetRemover; +import org.apache.drill.exec.store.jdbc.clickhouse.ClickhouseJdbcImplementor; + +public class JdbcSqlGenerator { + /** + * Generate sql for different jdbc databases + */ + public static String generateSql(JdbcStoragePlugin plugin, + RelOptCluster cluster, RelNode input) { + final SqlDialect dialect = plugin.getDialect(); + final JdbcImplementor jdbcImplementor; + if (plugin.getConfig().isClickhouse()) { Review comment: Here, we'd add a `generateSQL` method to our `JdbcDialect` interface, moving this code to subclasses as described above. ########## File path: contrib/storage-jdbc/src/main/java/org/apache/drill/exec/store/jdbc/JdbcSchemaFactory.java ########## @@ -0,0 +1,45 @@ +/* + * 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.drill.exec.store.jdbc; + +import org.apache.calcite.schema.SchemaPlus; +import org.apache.drill.exec.store.SchemaConfig; +import org.apache.drill.exec.store.jdbc.clickhouse.ClickhouseCatalogSchema; + +public class JdbcSchemaFactory { + private final JdbcStoragePlugin plugin; + + public JdbcSchemaFactory (JdbcStoragePlugin plugin) { + this.plugin = plugin; + } + + public void registerSchemas(SchemaConfig config, SchemaPlus parent) { + if (plugin.getConfig().isClickhouse()) { Review comment: Here we've added an `isClickhouse()` method to the base JDBC plugin. We might add five more "isDruid()", "isAthena()", "isNextBigThing()", ... Then we add logic in various places that use those queries. In doing so, we couple all these dialects and make the code harder to maintain. Suggestion: add a `getDialect()` method to the config. It returns a `JdbcDialect` subclass. `getDialect()` does what is needed to identify Clickhouse (or whatever) and return the specific dialect. Else, it returns a `GenericDialect` instance. One of the methods on `JdbcDialect` is `registerSchemas()`. The "then" part of this code goes in the Clickhouse version, the "else" part of this code goes into the `GenericDialect` version. Voila! No more tight coupling of dialects. Of course, if there is a better way to solve the problem, feel free to use that instead; the above is a quick & dirty example. -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
