Re: [PATCH] Add pg_get_policy_ddl() function to reconstruct CREATE POLICY statement

Hi Akshay,

v16 fixes both points from my last mail. Verified on master 5f14f82280:
builds, rowsecurity passes, and the s1.f/s2.f case now round-trips under a
hostile search_path. Nice that the rls_s1/rls_s2 test pins it.

I also diffed the generated DDL against pg_dump for the policies in the RLS
regression tests and pg_dump's own dump-test corpus (002_pg_dump.pl): they
match in every case except multi-role ordering (e.g. rls_p8 -- the function
keeps the declared order, TO regress_rls_dave, regress_rls_alice, while pg_dump
sorts by role OID), which doesn't matter since role order in a policy isn't
significant.

One thing left over from point 1: func-info.sgml doesn't state that object
references in the output are always schema-qualified. That's the function's
contract now, and it differs from pg_get_viewdef / ruledef (which follow the
caller's search_path), so a sentence would help. Empty search_path is also
exactly what pg_dump uses (ALWAYS_SECURE_SEARCH_PATH_SQL), so this is the
right call.

A tiny style nit, in pg_get_policy_ddl_internal():

Assert(!attrIsNull);
{
ArrayType *policy_roles = DatumGetArrayTypeP(valueDatum);

a blank line after the Assert would read a bit better.

Neither is a blocker -- looks ready to me.

Regards,
Rui