org.apache.flink.table.planner.catalog.CatalogCalciteSchema Maven / Gradle / Ivy

/*
 * 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.table.planner.catalog;

import org.apache.flink.annotation.Internal;
import org.apache.flink.table.catalog.CatalogManager;

import org.apache.calcite.linq4j.tree.Expression;
import org.apache.calcite.schema.Schema;
import org.apache.calcite.schema.SchemaPlus;
import org.apache.calcite.schema.Schemas;
import org.apache.calcite.schema.Table;

import java.util.HashSet;
import java.util.Set;

/**
 * A mapping between Flink's catalog and Calcite's schema. This enables to look up and access
 * objects(tables, views, functions, types) in SQL queries without registering them in advance.
 * Databases are registered as sub-schemas in the schema.
 */
@Internal
public class CatalogCalciteSchema extends FlinkSchema {

    private final String catalogName;
    private final CatalogManager catalogManager;
    // Flag that tells if the current planner should work in a batch or streaming mode.
    private final boolean isStreamingMode;

    public CatalogCalciteSchema(
            String catalogName, CatalogManager catalog, boolean isStreamingMode) {
        this.catalogName = catalogName;
        this.catalogManager = catalog;
        this.isStreamingMode = isStreamingMode;
    }

    /**
     * Look up a sub-schema (database) by the given sub-schema name.
     *
     * @param schemaName name of sub-schema to look up
     * @return the sub-schema with a given database name, or null
     */
    @Override
    public Schema getSubSchema(String schemaName) {
        if (catalogManager.schemaExists(catalogName, schemaName)) {
            return new DatabaseCalciteSchema(
                    schemaName, catalogName, catalogManager, isStreamingMode);
        } else {
            return null;
        }
    }

    @Override
    public Set getSubSchemaNames() {
        return catalogManager.listSchemas(catalogName);
    }

    @Override
    public Table getTable(String name) {
        return null;
    }

    @Override
    public Set getTableNames() {
        return new HashSet<>();
    }

    @Override
    public Expression getExpression(SchemaPlus parentSchema, String name) {
        return Schemas.subSchemaExpression(parentSchema, name, getClass());
    }

    @Override
    public boolean isMutable() {
        return true;
    }
}