public ResultSet getColumns()

in flight/flight-sql-jdbc-core/src/main/java/org/apache/arrow/driver/jdbc/ArrowDatabaseMetadata.java [969:1040]
61 lines of code
5 McCabe index (conditional complexity)

  public ResultSet getColumns(
      final String catalog,
      final String schemaPattern,
      final String tableNamePattern,
      final String columnNamePattern)
      throws SQLException {
    final ArrowFlightConnection connection = getConnection();
    final FlightInfo flightInfoTables =
        connection
            .getClientHandler()
            .getTables(catalog, schemaPattern, tableNamePattern, null, true);

    final BufferAllocator allocator = connection.getBufferAllocator();

    final Pattern columnNamePat =
        columnNamePattern != null ? Pattern.compile(sqlToRegexLike(columnNamePattern)) : null;

    return ArrowFlightJdbcFlightStreamResultSet.fromFlightInfo(
        connection,
        flightInfoTables,
        (originalRoot, transformedRoot) -> {
          int columnCounter = 0;
          if (transformedRoot == null) {
            transformedRoot = VectorSchemaRoot.create(GET_COLUMNS_SCHEMA, allocator);
          }

          final int originalRootRowCount = originalRoot.getRowCount();

          final VarCharVector catalogNameVector =
              (VarCharVector) originalRoot.getVector("catalog_name");
          final VarCharVector tableNameVector =
              (VarCharVector) originalRoot.getVector("table_name");
          final VarCharVector schemaNameVector =
              (VarCharVector) originalRoot.getVector("db_schema_name");

          final VarBinaryVector schemaVector =
              (VarBinaryVector) originalRoot.getVector("table_schema");

          for (int i = 0; i < originalRootRowCount; i++) {
            final Text catalogName = catalogNameVector.getObject(i);
            final Text tableName = tableNameVector.getObject(i);
            final Text schemaName = schemaNameVector.getObject(i);

            final Schema currentSchema;
            try {
              currentSchema =
                  MessageSerializer.deserializeSchema(
                      new ReadChannel(
                          Channels.newChannel(new ByteArrayInputStream(schemaVector.get(i)))));
            } catch (final IOException e) {
              throw new IOException(
                  String.format("Failed to deserialize schema for table %s", tableName), e);
            }
            final List<Field> tableColumns = currentSchema.getFields();

            columnCounter =
                setGetColumnsVectorSchemaRootFromFields(
                    transformedRoot,
                    columnCounter,
                    tableColumns,
                    catalogName,
                    tableName,
                    schemaName,
                    columnNamePat);
          }

          transformedRoot.setRowCount(columnCounter);

          originalRoot.clear();
          return transformedRoot;
        });
  }