![]() ![]() ![]() That is not limited to tables and views, but also extends to functions and operators. Since PostgreSQL parses the function body at query execution time, it uses the current setting of search_path to resolve all references to database objects that are not qualified with the schema name. However, it would be better to get an error message when we run DROP EXTENSION without using the CASCADE option. We will fix the problem by creating the extension again. You might need to add explicit type casts.ĬONTEXT: SQL function "mangle" during inlining HINT: No function matches the given name and argument types. The validator can also test if the objects referenced in the function exist, but it cannot keep you from later dropping an object used by the function.ĮRROR: function unaccent(text) does not exist A procedural language can provide a validator that checks the function body for syntactic correctness (if check_function_bodies = on). Since the body of a function is just a string constant that PostgreSQL cannot interpret, it won’t track dependencies between a function and objects used in the function. That way, the database knows the relationships between objects: it will either prevent you from dropping objects on which other objects depend (like a table with a foreign key reference) or drop dependent objects automatically (like dropping a table drops all indexes on the table). Usually, PostgreSQL tracks dependencies between database objects in the pg_depend and pg_shdepend catalog tables. This has some undesirable side effects: Lack of dependency tracking To allow that flexibility, the function body of a PostgreSQL function is simply a string constant that the call handler of the procedural language interprets when PostgreSQL executes the function. But that is not all: in PostgreSQL, you can write a plugin that allows you to use any language of your choice inside the database. Out of the box, PostgreSQL supports functions written in SQL, C, PL/pgSQL (a clone of Oracle’s PL/SQL), Perl, Python and Tcl. One of the nice aspects is that you are not restricted to a single programming language. ![]() Output: lower(unaccent('Schön dumm'::text)) We can see function inlining if we use EXPLAIN (VERBOSE) on our example function:ĮXPLAIN (VERBOSE, COSTS OFF) SELECT mangle('Schön dumm')
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