Hi Yuya, On Fri, Aug 25, 2023 at 1:09 PM Yuya Watari <watari.y...@gmail.com> wrote: > > 3. Future works > > 3.1. Redundant memory allocation of Lists > > When we need child EquivalenceMembers in a loop over ec_members, v20 > adds them to the list. However, since we cannot modify the ec_members, > v20 always copies it. In most cases, there are only one or two child > members, so this behavior is a waste of memory and time and not a good > idea. I didn't address this problem in v20 because doing so could add > much complexity to the code, but it is one of the major future works. > > I suspect that the degradation of Queries A and B is due to this > problem. The difference between 'make installcheck' and Queries A and > B is whether there are partitioned tables. Most of the tests in 'make > installcheck' do not have partitions, so find_relids_top_parents() > could immediately determine the given Relids are already top-level and > keep degradation very small. However, since Queries A and B have > partitions, too frequent allocations of Lists may have caused the > regression. I hope we can reduce the degradation by avoiding these > memory allocations. I will continue to investigate and fix this > problem. > > 3.2. em_relids and pull_varnos > > I'm sorry that v20 did not address your 1st concern regarding > em_relids and pull_varnos. I will try to look into this. > > 3.3. Indexes for RestrictInfos > > Indexes for RestrictInfos are still in RangeTblEntry in v20-0002. I > will also investigate this issue. > > 3.4. Correctness > > v20 has passed all regression tests in my environment, but I'm not so > sure if v20 is correct. > > 4. Conclusion > > I wrote v20 based on a new idea. It may have a lot of problems, but it > has advantages. At least it solves your 3rd concern. Since we iterate > Lists instead of Bitmapsets, we don't have to introduce an iterator > mechanism. My experiment showed that the 'make installcheck' > degradation was very small. For the 2nd concern, v20 no longer adds > child EquivalenceMembers to ec_members. I'm sorry if this is not what > you intended, but it effectively worked. Again, v20 is a new proof of > concept. I hope the v20-based approach will be a good alternative > solution if we can overcome several problems, including what I > mentioned above.
It seems that you are still investigating and fixing issues. But the CF entry is marked as "needs review". I think a better status is "WoA". Do you agree with that? -- Best Wishes, Ashutosh Bapat
