fe/src/main/java/org/apache/impala/analysis/TruncateStmt.java

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//   http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.impala.analysis;

import java.util.List;

import org.apache.impala.authorization.Privilege;
import org.apache.impala.catalog.FeFsTable;
import org.apache.impala.catalog.FeTable;
import org.apache.impala.common.AnalysisException;
import org.apache.impala.thrift.TTruncateParams;

import com.google.common.base.Preconditions;

/**
 * Representation of a TRUNCATE statement.
 * Acceptable syntax:
 *
 * TRUNCATE [TABLE] [IF EXISTS] [database.]table
 *
 */
public class TruncateStmt extends StatementBase {
  private TableName tableName_;
  private final boolean ifExists_;

  // Set in analyze().
  private FeTable table_;

  public TruncateStmt(TableName tableName, boolean ifExists) {
    Preconditions.checkNotNull(tableName);
    tableName_ = tableName;
    table_ = null;
    ifExists_ = ifExists;
  }

  @Override
  public void collectTableRefs(List<TableRef> tblRefs) {
    tblRefs.add(new TableRef(tableName_.toPath(), null));
  }

  @Override
  public void analyze(Analyzer analyzer) throws AnalysisException {
    tableName_ = analyzer.getFqTableName(tableName_);
    try {
      table_ = analyzer.getTable(tableName_, Privilege.INSERT);
    } catch (AnalysisException e) {
      if (ifExists_) return;
      throw e;
    }
    // We only support truncating hdfs tables now.
    if (!(table_ instanceof FeFsTable)) {
      throw new AnalysisException(String.format(
          "TRUNCATE TABLE not supported on non-HDFS table: %s", table_.getFullName()));
    }
    analyzer.checkTableCapability(table_, Analyzer.OperationType.WRITE);
  }

  @Override
  public String toSql(ToSqlOptions options) {
    return "TRUNCATE TABLE " + (ifExists_ ? " IF EXISTS " : "") + tableName_;
  }

  public TTruncateParams toThrift() {
    TTruncateParams params = new TTruncateParams();
    params.setTable_name(tableName_.toThrift());
    params.setIf_exists(ifExists_);
    return params;
  }
}