Explain EXPLAIN SYNTAX (children 1) SelectWithUnionQuery (children 1) ExpressionList (children 1) SelectQuery (children 2) ExpressionList (children 1) QualifiedAsterisk (children 2) Identifier columns_transformers ColumnsTransformerList (children 2) ColumnsReplaceTransformer (children 2) ColumnsReplaceTransformer::Replacement (children 1) Function plus (children 1) ExpressionList (children 2) Identifier j Literal UInt64_2 ColumnsReplaceTransformer::Replacement (children 1) Function plus (children 1) ExpressionList (children 2) Identifier i Literal UInt64_1 ColumnsApplyTransformer TablesInSelectQuery (children 1) TablesInSelectQueryElement (children 1) TableExpression (children 1) TableIdentifier columns_transformers