Postgres declare table as a parameter for a function?

I would like to create a function that operates on a table, for example

create or replace function test(t table) 
    returns void language plpgsql as
$func$
begin   
    select * from t limit 10;
end;
$func$

Then, I can call the function with any tablename, e.g.

select test(myTable);

How would I do something like this?

You cannot declare a table as function parameter per se, since there are no table variables in Postgres. But there are various ways to achieve what you might want to achieve - which isn't exactly clear yet.

You can "pass" a table as ...

-
... table name (type text or name) - especially when tables may not actually exist (yet):

• Define table and column names as arguments in a plpgsql function?

-
... object identifier (type regclass):

• PostgreSQL: Pass table as argument in function

• Table name as a PostgreSQL function parameter

-
... row type of the table (type anyelement) using the concept of polymorphism:

• Refactor a PL/pgSQL function to return the output of various SELECT queries

Typically, you end up using dynamic SQL in the function. Be wary of SQL injection vectors. Related:

• SQL injection in Postgres functions vs prepared queries

• PL/pgSQL regclass quoting of table named like keyword

The return type depends on your input and what you want to achieve ...

StackExchange Database Administrators Q#204639, answer score: 5