com.cloudera.impala.analysis.AlterTableDropColStmt.java Source code

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Here is the source code for com.cloudera.impala.analysis.AlterTableDropColStmt.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 org.apache.hadoop.hive.metastore.api.FieldSchema;

import com.cloudera.impala.catalog.HBaseTable;
import com.cloudera.impala.catalog.Table;
import com.cloudera.impala.common.AnalysisException;
import com.cloudera.impala.thrift.TAlterTableDropColParams;
import com.cloudera.impala.thrift.TAlterTableParams;
import com.cloudera.impala.thrift.TAlterTableType;
import com.google.common.base.Preconditions;

/**
 * Represents an ALTER TABLE DROP COLUMN statement.
 * Note: Hive does not support this syntax for droppping columns, but it is supported
 * by mysql.
 */
public class AlterTableDropColStmt extends AlterTableStmt {
    private final String colName_;

    public AlterTableDropColStmt(TableName tableName, String colName) {
        super(tableName);
        Preconditions.checkState(colName != null && !colName.isEmpty());
        colName_ = colName;
    }

    public String getColName() {
        return colName_;
    }

    @Override
    public TAlterTableParams toThrift() {
        TAlterTableParams params = super.toThrift();
        params.setAlter_type(TAlterTableType.DROP_COLUMN);
        TAlterTableDropColParams dropColParams = new TAlterTableDropColParams(colName_);
        params.setDrop_col_params(dropColParams);
        return params;
    }

    @Override
    public void analyze(Analyzer analyzer) throws AnalysisException {
        super.analyze(analyzer);
        Table t = getTargetTable();
        // TODO: Support column-level DDL on HBase tables. Requires updating the column
        // mappings along with the table columns.
        if (t instanceof HBaseTable) {
            throw new AnalysisException("ALTER TABLE DROP COLUMN not currently supported " + "on HBase tables.");
        }
        String tableName = getDb() + "." + getTbl();

        for (FieldSchema fs : t.getMetaStoreTable().getPartitionKeys()) {
            if (fs.getName().toLowerCase().equals(colName_.toLowerCase())) {
                throw new AnalysisException("Cannot drop partition column: " + fs.getName());
            }
        }

        if (t.getColumns().size() - t.getMetaStoreTable().getPartitionKeysSize() <= 1) {
            throw new AnalysisException(
                    String.format("Cannot drop column '%s' from %s. Tables must contain at least 1 column.",
                            colName_, tableName));
        }

        if (t.getColumn(colName_) == null) {
            throw new AnalysisException(
                    String.format("Column '%s' does not exist in table: %s", colName_, tableName));
        }
    }
}