private HBaseScanSpec createHBaseScanSpec()

in contrib/format-maprdb/src/main/java/org/apache/drill/exec/store/mapr/db/binary/MapRDBFilterBuilder.java [158:337]
156 lines of code
46 McCabe index (conditional complexity)

  private HBaseScanSpec createHBaseScanSpec(FunctionCall call, MaprDBCompareFunctionsProcessor processor) {
    String functionName = processor.getFunctionName();
    SchemaPath field = processor.getPath();
    byte[] fieldValue = processor.getValue();
    boolean sortOrderAscending = processor.isSortOrderAscending();
    boolean isRowKey = field.getRootSegmentPath().equals(ROW_KEY);
    if (!(isRowKey
        || (!field.getRootSegment().isLastPath()
            && field.getRootSegment().getChild().isLastPath()
            && field.getRootSegment().getChild().isNamed())
           )
        ) {
      /*
       * if the field in this function is neither the row_key nor a qualified HBase column, return.
       */
      return null;
    }

    if (processor.isRowKeyPrefixComparison()) {
      return createRowKeyPrefixScanSpec(call, processor);
    }

    CompareOp compareOp = null;
    boolean isNullTest = false;
    ByteArrayComparable comparator = new BinaryComparator(fieldValue);
    byte[] startRow = HConstants.EMPTY_START_ROW;
    byte[] stopRow = HConstants.EMPTY_END_ROW;
    switch (functionName) {
    case FunctionNames.EQ:
      compareOp = CompareOp.EQUAL;
      if (isRowKey) {
        startRow = fieldValue;
        /* stopRow should be just greater than 'value'*/
        stopRow = Arrays.copyOf(fieldValue, fieldValue.length+1);
        compareOp = CompareOp.EQUAL;
      }
      break;
    case FunctionNames.NE:
      compareOp = CompareOp.NOT_EQUAL;
      break;
    case FunctionNames.GE:
      if (sortOrderAscending) {
        compareOp = CompareOp.GREATER_OR_EQUAL;
        if (isRowKey) {
          startRow = fieldValue;
        }
      } else {
        compareOp = CompareOp.LESS_OR_EQUAL;
        if (isRowKey) {
          // stopRow should be just greater than 'value'
          stopRow = Arrays.copyOf(fieldValue, fieldValue.length+1);
        }
      }
      break;
    case FunctionNames.GT:
      if (sortOrderAscending) {
        compareOp = CompareOp.GREATER;
        if (isRowKey) {
          // startRow should be just greater than 'value'
          startRow = Arrays.copyOf(fieldValue, fieldValue.length+1);
        }
      } else {
        compareOp = CompareOp.LESS;
        if (isRowKey) {
          stopRow = fieldValue;
        }
      }
      break;
    case FunctionNames.LE:
      if (sortOrderAscending) {
        compareOp = CompareOp.LESS_OR_EQUAL;
        if (isRowKey) {
          // stopRow should be just greater than 'value'
          stopRow = Arrays.copyOf(fieldValue, fieldValue.length+1);
        }
      } else {
        compareOp = CompareOp.GREATER_OR_EQUAL;
        if (isRowKey) {
          startRow = fieldValue;
        }
      }
      break;
    case FunctionNames.LT:
      if (sortOrderAscending) {
        compareOp = CompareOp.LESS;
        if (isRowKey) {
          stopRow = fieldValue;
        }
      } else {
        compareOp = CompareOp.GREATER;
        if (isRowKey) {
          // startRow should be just greater than 'value'
          startRow = Arrays.copyOf(fieldValue, fieldValue.length+1);
        }
      }
      break;
    case FunctionNames.IS_NULL:
    case "isNull":
    case "is null":
      if (isRowKey) {
        return null;
      }
      isNullTest = true;
      compareOp = CompareOp.EQUAL;
      comparator = new NullComparator();
      break;
    case FunctionNames.IS_NOT_NULL:
    case "isNotNull":
    case "is not null":
      if (isRowKey) {
        return null;
      }
      compareOp = CompareOp.NOT_EQUAL;
      comparator = new NullComparator();
      break;
    case "like":
      /*
       * Convert the LIKE operand to Regular Expression pattern so that we can
       * apply RegexStringComparator()
       */
      HBaseRegexParser parser = new HBaseRegexParser(call).parse();
      compareOp = CompareOp.EQUAL;
      comparator = new RegexStringComparator(parser.getRegexString());

      /*
       * We can possibly do better if the LIKE operator is on the row_key
       */
      if (isRowKey) {
        String prefix = parser.getPrefixString();
        if (prefix != null) { // group 3 is literal
          /*
           * If there is a literal prefix, it can help us prune the scan to a sub range
           */
          if (prefix.equals(parser.getLikeString())) {
            /* The operand value is literal. This turns the LIKE operator to EQUAL operator */
            startRow = stopRow = fieldValue;
            compareOp = null;
          } else {
            startRow = prefix.getBytes(StandardCharsets.UTF_8);
            stopRow = startRow.clone();
            boolean isMaxVal = true;
            for (int i = stopRow.length - 1; i >= 0; --i) {
              int nextByteValue = (0xff & stopRow[i]) + 1;
              if (nextByteValue < 0xff) {
                stopRow[i] = (byte) nextByteValue;
                isMaxVal = false;
                break;
              } else {
                stopRow[i] = 0;
              }
            }
            if (isMaxVal) {
              stopRow = HConstants.EMPTY_END_ROW;
            }
          }
        }
      }
      break;
    }

    if (compareOp != null || startRow != HConstants.EMPTY_START_ROW || stopRow != HConstants.EMPTY_END_ROW) {
      Filter filter = null;
      if (isRowKey) {
        if (compareOp != null) {
          filter = new RowFilter(compareOp, comparator);
        }
      } else {
        byte[] family = HBaseUtils.getBytes(field.getRootSegment().getPath());
        byte[] qualifier = HBaseUtils.getBytes(field.getRootSegment().getChild().getNameSegment().getPath());
        filter = new SingleColumnValueFilter(family, qualifier, compareOp, comparator);
        ((SingleColumnValueFilter)filter).setLatestVersionOnly(true);
        if (!isNullTest) {
          ((SingleColumnValueFilter)filter).setFilterIfMissing(true);
        }
      }
      return new HBaseScanSpec(groupScan.getTableName(), startRow, stopRow, filter);
    }
    // else
    return null;
  }