CreateQuery t_merge_tree_index (children 3)
 Identifier t_merge_tree_index
 Columns definition (children 1)
  ExpressionList (children 3)
   ColumnDeclaration a (children 2)
    DataType UInt64
    Function CODEC (children 1)
     ExpressionList (children 1)
      Function LZ4
   ColumnDeclaration b (children 2)
    DataType UInt64
    Function CODEC (children 1)
     ExpressionList (children 1)
      Function LZ4
   ColumnDeclaration s (children 2)
    DataType String
    Function CODEC (children 1)
     ExpressionList (children 1)
      Function LZ4
 Storage definition (children 3)
  Function MergeTree
  Function tuple (children 1)
   ExpressionList (children 2)
    Identifier a
    Identifier b
  Set
