[GENERAL] Why is materialized view creation a "security-restricted operation"?

Hello,

I see this has been discussed briefly before[1], but I'm still not clear on what's happening and why.

I wrote a function that uses temporary tables in generating a result set. I can use it when creating tables or views, e.g.,

CREATE TABLE some_table AS SELECT * FROM my_func();

CREATE VIEW some_view AS SELECT * FROM my_func();

But creating a materialized view fails:

CREATE MATERIALIZED VIEW some_view AS SELECT * FROM my_func();

ERROR:  cannot create temporary table within security-restricted operation

The docs explain that this is expected[2], but not why. On the contrary, this is actually quite surprising to me, given that tables and views work just fine. What makes a materialized view so different? Are there any plans to make this more consistent?

Thanks for any help you can provide.

Regards,

Joshua Chamberlain

[1] https://www.postgresql.org/message-id/CAFjFpRcz3qKQFQo3RynfPinXdOp_42Tz%2BxCqBQdAoe061bMRSw%40mail.gmail.com

[2] https://www.postgresql.org/docs/9.3/static/sql-creatematerializedview.html