Explain EXPLAIN PIPELINE (children 1) SelectWithUnionQuery (children 1) ExpressionList (children 1) SelectQuery (children 4) ExpressionList (children 1) Asterisk TablesInSelectQuery (children 1) TablesInSelectQueryElement (children 1) TableExpression (children 1) Subquery (children 1) SelectWithUnionQuery (children 1) ExpressionList (children 1) SelectQuery (children 3) ExpressionList (children 1) Asterisk TablesInSelectQuery (children 1) TablesInSelectQueryElement (children 1) TableExpression (children 1) Function numbers (children 1) ExpressionList (children 1) Literal Float64_100000000 ExpressionList (children 1) Identifier number ExpressionList (children 1) Identifier number Set