对PostgreSQL语法分析中 targetlist 的理解

在 gram.y 中:

simple_select:                                
            SELECT    opt_distinct    target_list                    
            into_clause     from_clause     where_clause                    
            group_clause     having_clause    window_clause                    
                {                
                    SelectStmt *n = makeNode(SelectStmt);            
                    n->distinctClause = $2;            
                    n->targetList = $3;            
                    n->intoClause = $4;            
                    n->fromClause = $5;            
                    n->whereClause = $6;            
                    n->groupClause = $7;            
                    n->havingClause = $8;            
                    n->windowClause = $9;            
                    $$ = (Node *)n;            
                }                
                                
……       

把它修改一下，增加：

simple_select:                                
            SELECT    opt_distinct    target_list                    
            into_clause     from_clause     where_clause                    
            group_clause     having_clause    window_clause                    
                {                
                    SelectStmt *n = makeNode(SelectStmt);            
                    n->distinctClause = $2;            
                    n->targetList = $3;            
                    n->intoClause = $4;            
                    n->fromClause = $5;            
                    n->whereClause = $6;            
                    n->groupClause = $7;            
                    n->havingClause = $8;            
                    n->windowClause = $9;            
                    $$ = (Node *)n;
                    fprintf(stderr,"length of list: %d\n", n->targetList->length);
            
                }                
                                
……                                 

psql 中执行： select id, name from a8;

后台出现： length of list: 2