Re: Clarify "allow_system_table_mods"

* Melvin Davidson (melvin6925@gmail.com) wrote:
> Then could you please clarify exactly what structural mods are permitted by
> *"*
> *Allows modification of the structure of system tables" ?*

I would say, in short, those modifications which are implemented by PG
developers who know what's safe to do with the catalog tables.

Beyond that, I'm afriad you'd need to read the source code.  I don't
know offhand the complete set of "what's safe to do", though it's
probably a pretty short list and certainly doesn't include adding
columns.

Ultimately, that switch isn't for end users to use to modify the
catalogs.  If you'd like to modify the structure of pg_class, you would
start by looking at src/include/catalog/pg_class.h, though there's quite
a few other bits that would need to change too.

Thanks!

Stephen