SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 2)
    Identifier merge_algorithm
    Function if (children 1)
     ExpressionList (children 3)
      Function less (children 1)
       ExpressionList (children 2)
        Identifier peak_memory_usage
        Function multiply (children 1)
         ExpressionList (children 2)
          Function multiply (children 1)
           ExpressionList (children 2)
            Literal UInt64_500
            Literal UInt64_1024
          Literal UInt64_1024
      Literal \'OK\'
      Function format (children 1)
       ExpressionList (children 2)
        Literal \'FAIL: memory usage: {}\'
        Function formatReadableSize (children 1)
         ExpressionList (children 1)
          Identifier peak_memory_usage
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier system.part_log
   Function and (children 1)
    ExpressionList (children 4)
     Function equals (children 1)
      ExpressionList (children 2)
       Identifier database
       Function currentDatabase (children 1)
        ExpressionList
     Function equals (children 1)
      ExpressionList (children 2)
       Identifier table
       Literal \'t_vertical_merge_memory\'
     Function equals (children 1)
      ExpressionList (children 2)
       Identifier event_type
       Literal \'MergeParts\'
     Function equals (children 1)
      ExpressionList (children 2)
       Function length (children 1)
        ExpressionList (children 1)
         Identifier merged_from
       Literal UInt64_2
