presto-memory/src/main/java/io/prestosql/plugin/memory/MemoryMetadata.java/MemoryMetadata/dropTable
class MemoryMetadata:    @Override
    public synchronized void dropTable(ConnectorSession session, ConnectorTableHandle tableHandle)
    {
        MemoryTableHandle handle = (MemoryTableHandle) tableHandle;
        TableInfo info = tables.remove(handle.getId());
        if (info != null) {
            tableIds.remove(info.getSchemaTableName());
        }
    }