CreateQuery t_row_exists (children 3)
 Identifier t_row_exists
 Columns definition (children 1)
  ExpressionList (children 2)
   ColumnDeclaration a (children 1)
    DataType int
   ColumnDeclaration _row_exists (children 1)
    DataType int
 Storage definition (children 2)
  Function MergeTree
  Identifier a
