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Java-based middleware for in-memory processing of big data in a distributed environment.

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/*
 * 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.ignite.schema.parser.dialect;

import org.apache.ignite.schema.parser.*;

import java.sql.*;
import java.util.*;

/**
 * Base class for database metadata dialect.
 */
public abstract class DatabaseMetadataDialect {
    /**
     * Gets tables from database.
     *
     * @param conn Database connection.
     * @param tblsOnly If {@code true} then gets only tables otherwise gets tables and views.
     * @return Collection of table descriptors.
     * @throws SQLException If failed to get tables.
     */
    public abstract Collection tables(Connection conn, boolean tblsOnly) throws SQLException;

    /**
     * @return Collection of database system schemas.
     */
    public Set systemSchemas() {
        return Collections.singleton("INFORMATION_SCHEMA");
    }

    /**
     * Create table descriptor.
     *
     * @param schema Schema name.
     * @param tbl Table name.
     * @param cols Table columns.
     * @param idxs Table indexes.
     * @return New {@code DbTable} instance.
     */
    protected DbTable table(String schema, String tbl, Collection cols, Map>idxs) {
        Set ascCols = new HashSet<>();

        Set descCols = new HashSet<>();

        for (Map idx : idxs.values()) {
            if (idx.size() == 1)
                for (Map.Entry idxCol : idx.entrySet()) {
                    String colName = idxCol.getKey();

                    Boolean desc = idxCol.getValue();

                    if (desc != null) {
                        if (desc)
                            descCols.add(colName);
                        else
                            ascCols.add(colName);
                    }
                }
        }

        return new DbTable(schema, tbl, cols, ascCols, descCols, idxs);
    }
}