DropTableOrViewStmt.java

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// Copyright 2012 Cloudera Inc.
//
// Licensed 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 com.cloudera.impala.analysis;

import com.cloudera.impala.authorization.Privilege;
import com.cloudera.impala.catalog.Table;
import com.cloudera.impala.catalog.View;
import com.cloudera.impala.common.AnalysisException;
import com.cloudera.impala.thrift.TDropTableOrViewParams;
import com.cloudera.impala.thrift.TTableName;
import com.google.common.base.Preconditions;

public class DropTableOrViewStmt extends StatementBase {
  protected final TableName tableName_;
  protected final boolean ifExists_;

  // True if we are dropping a table. False if we are dropping a view.
  protected final boolean dropTable_;

  // Set during analysis
  protected String dbName_;

  public DropTableOrViewStmt(TableName tableName, boolean ifExists, boolean dropTable) {
    this.tableName_ = tableName;
    this.ifExists_ = ifExists;
    this.dropTable_ = dropTable;
  }

  @Override
  public String toSql() {
    StringBuilder sb = new StringBuilder("DROP " + ((dropTable_) ? "TABLE" : "VIEW"));
    if (ifExists_) sb.append("IF EXISTS ");
    if (tableName_.getDb() != null) sb.append(tableName_.getDb() + ".");
    sb.append(tableName_.getTbl());
    return sb.toString();
  }

  public TDropTableOrViewParams toThrift() {
    TDropTableOrViewParams params = new TDropTableOrViewParams();
    params.setTable_name(new TTableName(getDb(), getTbl()));
    params.setIf_exists(getIfExists());
    return params;
  }

  @Override
  public void analyze(Analyzer analyzer) throws AnalysisException {
    dbName_ = analyzer.getTargetDbName(tableName_);
    try {
      Table table = analyzer.getTable(tableName_, Privilege.DROP);
      Preconditions.checkNotNull(table);
      if (table instanceof View && dropTable_) {
        throw new AnalysisException(String.format(
            "DROP TABLE not allowed on a view: %s.%s", dbName_, getTbl()));
      }
      if (!(table instanceof View) && !dropTable_) {
        throw new AnalysisException(String.format(
            "DROP VIEW not allowed on a table: %s.%s", dbName_, getTbl()));
      }
    } catch (AnalysisException e) {
      if (ifExists_ && analyzer.getMissingTbls().isEmpty()) return;
      throw e;
    }
  }

  public String getDb() {
    Preconditions.checkNotNull(dbName_);
    return dbName_;
  }

  public String getTbl() { return tableName_.getTbl(); }
  public boolean getIfExists() { return this.ifExists_; }
  public boolean isDropTable() { return dropTable_; }
}