SelectWithUnionQuery (children 1) ExpressionList (children 1) SelectQuery (children 4) ExpressionList (children 1) Function sipHash64 (children 1) ExpressionList (children 1) Identifier x TablesInSelectQuery (children 1) TablesInSelectQueryElement (children 1) TableExpression (children 2) TableIdentifier tab SampleRatio 1 / 2 ExpressionList (children 2) OrderByElement (children 1) Identifier x OrderByElement (children 1) Function sipHash64 (children 1) ExpressionList (children 1) Identifier x Literal UInt64_5