protected HashSet<Pair<Text,Text>> getPairCollection(List<ColumnMapping> columnMappings) {
    final HashSet<Pair<Text,Text>> pairs = new HashSet<Pair<Text,Text>>();

    for (ColumnMapping columnMapping : columnMappings) {
      if (columnMapping instanceof HiveAccumuloColumnMapping) {
        HiveAccumuloColumnMapping accumuloColumnMapping = (HiveAccumuloColumnMapping) columnMapping;

        Text cf = new Text(accumuloColumnMapping.getColumnFamily());
        Text cq = null;

        // A null cq implies an empty column qualifier
        if (null != accumuloColumnMapping.getColumnQualifier()) {
          cq = new Text(accumuloColumnMapping.getColumnQualifier());
        }

        pairs.add(new Pair<Text,Text>(cf, cq));
      } else if (columnMapping instanceof HiveAccumuloMapColumnMapping) {
        HiveAccumuloMapColumnMapping mapMapping = (HiveAccumuloMapColumnMapping) columnMapping;

        // Can't fetch prefix on colqual, must pull the entire qualifier
        // TODO use an iterator to do the filter, server-side.
        pairs.add(new Pair<Text,Text>(new Text(mapMapping.getColumnFamily()), null));
      }
    }

    log.info("Computed columns to fetch (" + pairs + ") from " + columnMappings);

    return pairs;
  }
Create col fam/qual pairs from pipe separated values, usually from config object. Ignores
rowID.

@param columnMappings
         The list of ColumnMappings for the given query
@return a Set of Pairs of colfams and colquals
accumulo-handler/src/java/org/apache/hadoop/hive/accumulo/mr/HiveAccumuloTableInputFormat.java