presto-memory/src/main/java/io/prestosql/plugin/memory/MemoryMetadata.java/MemoryMetadata/updateRowsOnHosts
class MemoryMetadata:    private void updateRowsOnHosts(long tableId, Collection<Slice> fragments)
    {
        TableInfo info = tables.get(tableId);
        checkState(
                info != null,
                "Uninitialized tableId [%s.%s]",
                info.getSchemaName(),
                info.getTableName());

        Map<HostAddress, MemoryDataFragment> dataFragments = new HashMap<>(info.getDataFragments());
        for (Slice fragment : fragments) {
            MemoryDataFragment memoryDataFragment = MemoryDataFragment.fromSlice(fragment);
            dataFragments.merge(memoryDataFragment.getHostAddress(), memoryDataFragment, MemoryDataFragment::merge);
        }

        tables.put(tableId, new TableInfo(tableId, info.getSchemaName(), info.getTableName(), info.getColumns(), dataFragments));
    }