Stephen Frost wrote: > KaiGai, > > * KaiGai Kohei (kai...@ak.jp.nec.com) wrote: >>> Is it possible to implement a walker function to pick up appeared >>> columns and to chain them on rte->cols_sel/cols_mod? >>> In this idea, columns in Query->targetList should be chained on >>> rte->cols_mod, and others should be chained on rte->cols_sel. > > This sounds like a reasonable approach to me, but as I mentioned before, > I'm not very familiar with the analyzer and company. > >> The attached patch is a proof of the concept. > > Excellent, I'll play around with it. > >> Any comment? > > I'm generally not a huge fan of recursion simply because it's often > overrated and overused and implements a limit based on stack depth which > can cause unexpected failures. Can we be confident that the recursion > added here doesn't add a new limit on the size/complexity of queries > which, if hit, will cause a stack overflow? I notice that we do use > recursion in some other places, but we also occationally have checks to > prevent recursing too far.
I think it does not give us any other new size/complexity limitation, because we already have some of recursive walker functions which consume stack more than applyColumnPrivsWalker() I proposed. The applyColumnPrivsWalker() consumes its stack for a return address, two pointers and an integer variables for each depth. But, for example, existing check_ungrouped_columns_walker() consumes it more. In addition, please note that expression_tree_walker() invokes check_stack_depth() to prevent unexpected stack overflow. Thanks, >> I strongly want the Column-level privileges to be get merged >> as soon as possible, so I don't spare any possible assist >> for his works. > > Thanks so much for your help! It's definitely appriciated. I'm going > to try and play with your patch today and probably add some additional > regression tests and make sure everything works as expected. > > Thanks again! > > Stephen -- OSS Platform Development Division, NEC KaiGai Kohei <kai...@ak.jp.nec.com> -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
