postgreSQL解释分析一个函数

我试图理解 postgresql中的查询优化,我有一个函数,里面有一些查询.其中一些是简单的查询,它将值保存到变量中,然后下一个查询将此变量用于查找内容..让我们说：

function()...
select type into t
from tableA
where code = a_c;

select num into n
from tableB
where id = t; 
end function...

还有更多..如果我想解释分析整个函数我执行命令说明解析select function();这是正确的方法吗？或者我应该解释分析函数内的每个查询,如果是这样的话,用什么值？

考虑使用 auto_explain模块：

The auto_explain module provides a means for logging execution plans
of slow statements automatically,without having to run EXPLAIN by
hand. This is especially helpful for tracking down un-optimized
queries in large applications.

打开auto_explain.log_nested_statements：

auto_explain.log_nested_statements (boolean)

auto_explain.log_nested_statements causes nested statements
(statements executed inside a function) to be considered for logging. When it is off,only top-level query plans are logged. This parameter is off by default. Only superusers can change this setting.