Explain EXPLAIN PIPELINE (children 2)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 4)
    ExpressionList (children 1)
     Asterisk
    TablesInSelectQuery (children 1)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       TableIdentifier tab
    ExpressionList (children 1)
     OrderByElement (children 1)
      Identifier t
    Set
 Identifier tsv
