Deleting an Index

Function

You can manage HBase secondary indexes using methods provided in org.apache.hadoop.hbase.hindex.client.HIndexAdmin. This class provides methods of querying and deleting an index.

Example Code

The following code snippet belongs to the dropIndex method in the HBaseSample class of the com.huawei.bigdata.hbase.examples package.

public void dropIndex() {
    LOG.info("Entering dropIndex.");
    String indexName = "index_name";
    List<String> indexNameList = new ArrayList<String>();
    indexNameList.add(indexName);

    IndexAdmin iAdmin = null;
    try {
      // Instantiate HIndexAdmin Object
      iAdmin = HIndexClient.newHIndexAdmin(conn.getAdmin());
      // Delete Secondary Index
      iAdmin.dropIndex(tableName, indexNameList);

      LOG.info("Drop index successfully.");
    } catch (IOException e) {
      LOG.error("Drop index failed.");
    } finally {
      if (iAdmin != null) {
        try {
          // Close Secondary Index
          iAdmin.close();
        } catch (IOException e) {
          LOG.error("Close admin failed.");
        }
      }
    }
    LOG.info("Exiting dropIndex.");
  } 

Precautions

• Use the dropIndex and dropIndexes interfaces to delete HBase level-2 indexes. Do not directly drop the index table, because it is an invalid operation and cannot update table information, leading to query failures at the time of index rebuilding.
• If a user table is deleted, the corresponding index table is also deleted.