识别处于活动状态的定向查询

多个定向查询可以映射到同一输入查询。系统表 DIRECTED_QUERIES 中的 is_active 列标识处于活动状态的定向查询。如果多个定向查询对于同一输入查询均处于活动状态，优化器则使用要创建的第一个定向查询。在这种情况下，可使用 EXPLAIN 识别哪个定向查询处于活动状态。

DIRECTED_QUERIES 上的以下查询查找所有处于活动状态的定向查询，且其中的输入查询包含被查询表 employee_dimension 的名称：

=> SELECT * FROM directed_queries WHERE input_query ILIKE ('%employee_dimension%') AND is_active='t';
-[ RECORD 1 ]------+
query_name         | findEmployeesCityJobTitle_OPT
is_active          | t
vertica_version    | Vertica Analytic Database v11.0.1-20210815
comment            | Optimizer-generated directed query
save_plans_version | 0
username           | dbadmin
creation_date      | 2021-08-20 14:53:42.323963
since_date         |
input_query        | SELECT employee_dimension.employee_first_name, employee_dimension.employee_last_name FROM public.employee_dimension WHERE ((employee_dimension.employee_city = 'Boston'::varchar(6) /*+:v(1)*/) AND (employee_dimension.job_title = 'Cashier'::varchar(7) /*+:v(2)*/)) ORDER BY employee_dimension.employee_last_name, employee_dimension.employee_first_name
annotated_query    | SELECT /*+verbatim*/  employee_dimension.employee_first_name, employee_dimension.employee_last_name FROM public.employee_dimension employee_dimension/*+projs('public.employee_dimension')*/ WHERE ((employee_dimension.employee_city = 'Boston'::varchar(6) /*+:v(1)*/) AND (employee_dimension.job_title = 'Cashier'::varchar(7) /*+:v(2)*/)) ORDER BY employee_dimension.employee_last_name, employee_dimension.employee_first_name

如果对输入查询运行 EXPLAIN，它将返回一个确认使用 findEmployeesCityJobTitle_OPT 作为活动定向查询的查询计划：

=> EXPLAIN SELECT employee_first_name, employee_last_name FROM employee_dimension WHERE employee_city='Boston' AND job_title ='Cashier' ORDER BY employee_last_name, employee_first_name;

 The following active directed query(query name: findEmployeesCityJobTitle_OPT) is being executed:
 SELECT /*+verbatim*/  employee_dimension.employee_first_name, employee_dimension.employee_last_name FROM public.employee_dimension employee_dimension/*+projs('public.employee_dimension')*/ WHERE ((employee_dimension.employee_city = 'Boston'::varchar(6)) AND (employee_dimension.job_title = 'Cashier'::varchar(7))) ORDER BY employee_dimension.employee_last_name, employee_dimension.employee_first_name