Thread

Re: Clarification on when _PG_init() is invoked for extensions

Rahila Syed <rahilasyed90@gmail.com> — 2025-11-21T04:28:23Z

Hi,


>
> CREATE extension does not automatically load or ensure that _PG_init() is
>> run.
>> It mainly runs the .sql script in your extension.
>>
> Thanks for the clarification. However, in my testing, _PG_init() did run
> when I executed
> CREATE EXTENSION. I suspect this might be happening because the SQL
> script defines
> C functions using MODULE_PATHNAME, which triggers the library load.
> In a new session, _PG_init() seems to run again when any of those C
> functions are executed.
>
>
You are right, if the create extension creates a C function it triggers the
load of the library, which
in turn causes _PG_init() to execute.
Sorry for the confusion.

FWIW, the call stack looks like the following:
_PG_init ()
internal_load_library()
load_external_function ()
fmgr_c_validator ()
FunctionCall1Coll ()
OidFunctionCall1Coll ()
ProcedureCreate ()
CreateFunction ()
ProcessUtilitySlow ()
standard_ProcessUtility ()
ProcessUtility ()
execute_sql_string ()
execute_extension_script ()
CreateExtensionInternal ()
CreateExtension ()

Thank you,
Rahila Syed

>