如何在PostgreSQL中复制函数

Question

I want to write sqitch deploy script to create new version of trigger. To ensure that revert script will revert function to previous version, I'd like to make a backup of this function. Is there any way to copy (RENAME TO is not working!) trigger function with new name?

Answer 1

RENAME TO should work. Are you forgetting parentheses or including them on the other side?

Parentheses with alter table rename are a little tricky:

postgres=# create function test() returns bool language sql as $$ select true; $$;
CREATE FUNCTION
postgres=# alter function test() rename to old_test();
ERROR:  syntax error at or near "("
LINE 1: alter function test() rename to old_test();
                                                ^
postgres=# alter function test() rename to old_test;
ALTER FUNCTION

If that is not enough, then you could DO and EXECUTE the output of pg_get_functiondef after parsing and renaming it:

select * from pg_get_functiondef('old_test'::regproc);