public static Schema jdbcToArrowSchema()

in adapter/jdbc/src/main/java/org/apache/arrow/adapter/jdbc/JdbcToArrowUtils.java [273:344]
67 lines of code
12 McCabe index (conditional complexity)

  public static Schema jdbcToArrowSchema(ResultSetMetaData rsmd, JdbcToArrowConfig config)
      throws SQLException {
    Preconditions.checkNotNull(rsmd, "JDBC ResultSetMetaData object can't be null");
    Preconditions.checkNotNull(config, "The configuration object must not be null");

    List<Field> fields = new ArrayList<>();
    int columnCount = rsmd.getColumnCount();
    for (int i = 1; i <= columnCount; i++) {
      final String columnName = rsmd.getColumnLabel(i);

      final Map<String, String> columnMetadata =
          config.getColumnMetadataByColumnIndex() != null
              ? config.getColumnMetadataByColumnIndex().get(i)
              : null;
      final Map<String, String> metadata;
      if (config.shouldIncludeMetadata()) {
        metadata = new HashMap<>();
        metadata.put(Constants.SQL_CATALOG_NAME_KEY, rsmd.getCatalogName(i));
        metadata.put(Constants.SQL_SCHEMA_NAME_KEY, rsmd.getSchemaName(i));
        metadata.put(Constants.SQL_TABLE_NAME_KEY, rsmd.getTableName(i));
        metadata.put(Constants.SQL_COLUMN_NAME_KEY, columnName);
        metadata.put(Constants.SQL_TYPE_KEY, rsmd.getColumnTypeName(i));
        if (columnMetadata != null && !columnMetadata.isEmpty()) {
          metadata.putAll(columnMetadata);
        }
      } else {
        if (columnMetadata != null && !columnMetadata.isEmpty()) {
          metadata = columnMetadata;
        } else {
          metadata = null;
        }
      }

      final JdbcFieldInfo columnFieldInfo = getJdbcFieldInfoForColumn(rsmd, i, config);
      final ArrowType arrowType = config.getJdbcToArrowTypeConverter().apply(columnFieldInfo);
      if (arrowType != null) {
        final FieldType fieldType =
            new FieldType(
                isColumnNullable(rsmd, i, columnFieldInfo),
                arrowType, /* dictionary encoding */
                null,
                metadata);

        List<Field> children = null;
        if (arrowType.getTypeID() == ArrowType.List.TYPE_TYPE) {
          final JdbcFieldInfo arrayFieldInfo = getJdbcFieldInfoForArraySubType(rsmd, i, config);
          if (arrayFieldInfo == null) {
            throw new IllegalArgumentException(
                "Configuration does not provide a mapping for array column " + i);
          }
          children = new ArrayList<Field>();
          final ArrowType childType = config.getJdbcToArrowTypeConverter().apply(arrayFieldInfo);
          children.add(new Field("child", FieldType.nullable(childType), null));
        } else if (arrowType.getTypeID() == ArrowType.ArrowTypeID.Map) {
          FieldType mapType = new FieldType(false, ArrowType.Struct.INSTANCE, null, null);
          FieldType keyType = new FieldType(false, new ArrowType.Utf8(), null, null);
          FieldType valueType = new FieldType(false, new ArrowType.Utf8(), null, null);
          children = new ArrayList<>();
          children.add(
              new Field(
                  "child",
                  mapType,
                  Arrays.asList(
                      new Field(MapVector.KEY_NAME, keyType, null),
                      new Field(MapVector.VALUE_NAME, valueType, null))));
        }

        fields.add(new Field(columnName, fieldType, children));
      }
    }
    return new Schema(fields, config.getSchemaMetadata());
  }