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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.drill.exec.planner.sql.handlers;
import static org.apache.drill.exec.planner.sql.parser.DrillParserUtil.CHARSET;
import java.util.List;
import net.hydromatic.optiq.SchemaPlus;
import net.hydromatic.optiq.tools.Planner;
import net.hydromatic.optiq.tools.RelConversionException;
import org.apache.drill.exec.ops.QueryContext;
import org.apache.drill.exec.planner.sql.parser.DrillParserUtil;
import org.apache.drill.exec.planner.sql.parser.SqlShowTables;
import org.apache.drill.exec.store.AbstractSchema;
import org.eigenbase.sql.SqlIdentifier;
import org.eigenbase.sql.SqlLiteral;
import org.eigenbase.sql.SqlNode;
import org.eigenbase.sql.SqlNodeList;
import org.eigenbase.sql.SqlSelect;
import org.eigenbase.sql.fun.SqlStdOperatorTable;
import org.eigenbase.sql.parser.SqlParserPos;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;
public class ShowTablesHandler extends DefaultSqlHandler {
public ShowTablesHandler(Planner planner, QueryContext context) { super(planner, context); }
/** Rewrite the parse tree as SELECT ... FROM INFORMATION_SCHEMA.`TABLES` ... */
@Override
public SqlNode rewrite(SqlNode sqlNode) throws RelConversionException{
SqlShowTables node = unwrap(sqlNode, SqlShowTables.class);
List<SqlNode> selectList = Lists.newArrayList();
SqlNode fromClause;
SqlNode where;
// create select columns
selectList.add(new SqlIdentifier("TABLE_SCHEMA", SqlParserPos.ZERO));
selectList.add(new SqlIdentifier("TABLE_NAME", SqlParserPos.ZERO));
fromClause = new SqlIdentifier(ImmutableList.of("INFORMATION_SCHEMA", "TABLES"), SqlParserPos.ZERO);
final SqlIdentifier db = node.getDb();
String tableSchema;
if (db != null) {
tableSchema = db.toString();
} else {
// If no schema is given in SHOW TABLES command, list tables from current schema
SchemaPlus schema = context.getNewDefaultSchema();
if (isRootSchema(schema)) {
// If the default schema is a root schema, throw an error to select a default schema
throw new RelConversionException("No schema selected. Select a schema using 'USE schema' command");
}
AbstractSchema drillSchema;
try {
drillSchema = getDrillSchema(schema);
} catch(Exception ex) {
throw new RelConversionException("Error while rewriting SHOW TABLES query: " + ex.getMessage(), ex);
}
tableSchema = drillSchema.getFullSchemaName();
}
where = DrillParserUtil.createCondition(
new SqlIdentifier("TABLE_SCHEMA", SqlParserPos.ZERO),
SqlStdOperatorTable.EQUALS,
SqlLiteral.createCharString(tableSchema, CHARSET, SqlParserPos.ZERO));
SqlNode filter = null;
final SqlNode likePattern = node.getLikePattern();
if (likePattern != null) {
filter = DrillParserUtil.createCondition(
new SqlIdentifier("TABLE_NAME", SqlParserPos.ZERO),
SqlStdOperatorTable.LIKE,
likePattern);
} else if (node.getWhereClause() != null) {
filter = node.getWhereClause();
}
where = DrillParserUtil.createCondition(where, SqlStdOperatorTable.AND, filter);
return new SqlSelect(SqlParserPos.ZERO, null, new SqlNodeList(selectList, SqlParserPos.ZERO),
fromClause, where, null, null, null, null, null, null);
}
}
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