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Re: Changing a schema's name with function1 calling function2

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On 12/24/23 13:43, Peter J. Holzer wrote:
On 2023-12-23 08:31:39 -0800, Adrian Klaver wrote:


I think you misunderstood Wilma. What she is asking for is a "keyword"
or "magic variable" (or whatever you want to call it) which you can
specify in CREATE|ALTER FUNCTION ... SET SEARCH_PATH = ..., which refers
to the schema the function is (being) created in.

Maybe, but I don't think so. From one of Wilma's previous post:

"Therefore it would be great if there was a variable which I could set in a search_path (like the variable "$user") which denotes the function's schema and which is only evaluated when the function is executed, i.e. the variable would be the value of the function's search_path in the function's meta data. This variable, e.g. "$function_schema" would still denote the correct schema after renaming the schema."

It seems to be pretty tied to search_path. Now there is, from:

https://www.postgresql.org/docs/current/catalog-pg-proc.html

proconfig text[]

Function's local settings for run-time configuration variables

Though that is part of the function definition not the code inside the function as you show below. Also you would still need to determine what was the appropriate schema before creating/altering the setting for the function.

There is also:

pronamespace oid (references pg_namespace.oid)

The OID of the namespace that contains this function

which could be construed as '... the function meta data.', though its not strictly search_path. I could see that being part of some dynamic SQL to set the search_path.



So if you create the function with

     create function foo (...)
     set search_path to __function_schema__
     $$ ... $$

(using the "dunder" convention (from some other programming languages)
to denote the magic variable/keyword)

the search path would be set to whatever schema was first in the
search_path when the function was created.

That assumes the first schema is the correct one. Not something that could be counted on given search_path can be set any number of ways at any time.


If you create it with

     create function my_schema.foo (...)
     set search_path to __function_schema__
     $$ ... $$

it would be set to "my_schema".

And if you changed the schema with

     alter function foo set schema my_new_schema

it would be changed to "my_new_schema".

Personally I think that effect should be easy enough to create in your
deployment or migration scripts but of course that assumes that you have
such scripts. If you are doing your deployments manually (especially by
cloning a template as described by Wilma) I can see how that feature
would make things easier and/or reduce the risk of errors.

         hp


--
Adrian Klaver
adrian.klaver@xxxxxxxxxxx






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