HI,
On Nov 7, 2022, 04:12 +0800, Tom Lane <t...@sss.pgh.pa.us>, wrote: > > The NIL lists are of course occupying no storage. The two one-element > lists are absolutely, completely negligible in the context of planning > any nontrivial statement. Even the aggtransinfos list that is the > primary output of preprocess_aggref will dwarf that; and we leak > similarly small data structures in probably many hundred places in > the planner. > > I went a bit further and ran the core regression tests, then aggregated > the results: > > $ grep 'leaking list' postmaster.log | sed 's/.*] //' | sort | uniq -c > 4516 LOG: leaking list of length 0 > 95 LOG: leaking list of length 1 > 15 LOG: leaking list of length 2 > > You can quibble of course about how representative the regression tests > are, but there's sure no evidence at all here that we'd be saving > anything measurable. > > If anything, I'd be inclined to get rid of the > > list_free(*same_input_transnos); > > in find_compatible_agg, because it seems like a waste of code on > the same grounds. Instrumenting that in the same way, I find > that it's not reached at all in your example, while the > regression tests give > > 49 LOG: freeing list of length 0 > 2 LOG: freeing list of length 1 > Thanks for the investigation. Yeah, this patch is negligible. I’ll withdraw it in CF. Regards, Zhang Mingli
