On Mon, Sep 26, 2011 at 3:59 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Kohei KaiGai <kai...@kaigai.gr.jp> writes: >> Sorry, are you saying the current (in other words, rte->security_barrier >> stores the state of reloption) approach is not a good idea? > > Yes. I think the same as Robert: the way to handle this is to store it > in RelOptInfo for the duration of planning, and pull it from the > catalogs during planner startup (cf plancat.c).
Having looked at this more, I'm starting to believe KaiGai has this part right after all. The trouble is that the rewriter does this: /* * Now, plug the view query in as a subselect, replacing the relation's * original RTE. */ rte = rt_fetch(rt_index, parsetree->rtable); rte->rtekind = RTE_SUBQUERY; rte->relid = InvalidOid; rte->subquery = rule_action; rte->inh = false; /* must not be set for a subquery */ In other words, by the time the planner comes along and tries to decide whether or not it should flatten this subquery, the view has already been rewritten into a subquery - and that subquery is in most respects indistinguishable from a subquery that the user wrote directly. There is one difference: the permission check that would have been done against the view gets attached to the OLD entry in the subquery's range table. It would probably be possible to make this work by having the code paths that need to know whether or not a given subquery originated from a security-barrier-enabled view do that same trick: peek down into the OLD entry in the subquery rangetable, extract the view OID from there, and go check its reloptions. But that seems awfully complicated and error-prone, hence my feeling that just flagging the subquery explicitly is probably a better approach. One other possibility that comes to mind is that, instead of adding "bool security_view" to the RTE, we could instead add a new RTEKind, something like RTE_SECURITY_VIEW. That would mean going through and finding all the places that refer to RTE_SUBQUERY and adjusting them to handle RTE_SECURITY_VIEW in either the same way or differently as may be appropriate. The possible advantage of this approach is that it doesn't bloat the RTE structure (and stored rules that use it) with an additional attribute that (I think) will always be false - because security_barrier can only be set on a subquery RTE after rewriting has happened, and stored rules are haven't been rewritten yet. It might also force people to think a bit more carefully about how security views should be handled during future code changes, which could also be viewed as a plus. I'm attaching my current version of KaiGai's patch (with substantial cleanup of the comments and documentation, and some other changes) for reference. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
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