PostgreSQL：将表值函数连续应用于一组值和UNION ALL结果 [英] PostgreSQL: Serially apply table-valued function to a set of values and UNION ALL results
问题描述
我有一个表值PL / pgsql函数，它作为1输入一个整数，一个ID。返回的表具有固定列（例如5），但行数不同。
I have a table-valued PL/pgsql function that takes as 1 input an integer, an ID. The table that is returned has fixed columns (say 5) but varying number of rows.
有一个包含这些唯一ID的大表格。我想将此函数应用于每个ID和UNION的所有结果。
There is a large table of these unique IDs. I'd like to apply this function to each ID and UNION ALL the results.
查看在线我一直看到CROSS APPLY作为解决方案，但它似乎在PostgreSQL中不可用。我如何做这个应用操作？
Looking online I keep seeing CROSS APPLY as the solution, but it does not appear to be available in PostgreSQL. How can I do this "apply" operation?
一个简单的解决方案是用额外的外部循环重写表值函数。
One trivial solution is to re-write the table-valued function with an additional outer loop. But is there a way to do this directly in SQL?
推荐答案
我认为在当前版本的PostgreSQL中是不可能做到的）。在9.3中，会有 LATERAL加入，这完全符合您的需要。
I think it's impossible to do in current version of PostgreSQL (9.2). In 9.3 there would be LATERAL join which does exactly what you want.
但是， apply 函数返回一组简单的值：
You can, however, apply function returning set of simple values:
select id, func(id) as f from tbl1
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