On 19 July 2013 04:09, Greg Smith <g...@2ndquadrant.com> wrote:
> On 7/18/13 11:03 PM, Stephen Frost wrote:
>> Wasn't there a wiki page about this
>> feature which might also help?  Bigger question- is it correct for the
>> latest version of the patch?
> https://wiki.postgresql.org/wiki/RLS has accumulated a lot of older debris
> that may or may not be useful here.
> This useful piece was just presented at PGCon:
> http://www.pgcon.org/2013/schedule/attachments/273_PGcon2013-kaigai-row-level-security.pdf
> That is very up to date intro to the big picture issues.


I took a look at this patch too. I didn't read all the code in detail,
but there was one area I wondered about --- is it still necessary to
add the new field rowsec_relid to RangeTblEntry?

As far as I can see, it is only used in the new function getrelid()
which replaces the old macro of the same name, so that it can work if
it is passed the index of the sourceRelation subquery RTE instead of
the resultRelation. This seems to be encoding a specific assumption
that a subquery RTE is always going to come from row-level security

Is it the case that this can only happen from expand_targetlist(), in
which case why not pass both source_relation and result_relation to
expand_targetlist(), which I think will make that code neater. As it
stands, what expand_targetlist() sees as result_relation is actually
source_relation, which getrelid() then handles specially. Logically I
think expand_targetlist() should pass the actual result_relation to
getrelid(), opening the target table, and then pass source_relation to
makeVar() when building new TLEs.

With that change to expand_targetlist(), the change to getrelid() may
be unnecessary, and then also the new rowsec_relid field in
RangeTblEntry may not be needed.


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