Re: sqlsmith crash incremental sort
От | Tomas Vondra |
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Тема | Re: sqlsmith crash incremental sort |
Дата | |
Msg-id | 20200423095700.2iwhfiqjqy7lgzbk@development обсуждение исходный текст |
Ответ на | Re: sqlsmith crash incremental sort (Richard Guo <guofenglinux@gmail.com>) |
Ответы |
Re: sqlsmith crash incremental sort
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Список | pgsql-hackers |
On Thu, Apr 23, 2020 at 03:28:21PM +0800, Richard Guo wrote: >On Thu, Apr 23, 2020 at 6:59 AM Tomas Vondra <tomas.vondra@2ndquadrant.com> >wrote: > >> I've pushed fix with the DEFAULT_NUM_DISTINCT. The input comes from a >> set operation (which is where we call generate_append_tlist), so it's >> probably fairly unique, so maybe we should use input_tuples. But it's >> not guaranteed, so DEFAULT_NUM_DISTINCT seems reasonably defensive. >> > >Thanks for the fix. Verified that the crash has been fixed. > > >> >> One detail I've changed is that instead of matching the expression >> directly to a Var, it now calls pull_varnos() to also detect Vars >> somewhere deeper. Lookig at examine_variable() it calls find_base_rel >> for such case too, but I haven't tried constructing a query triggering >> the issue. >> > >A minor comment is that I don't think we need to strip relabel >explicitly before calling pull_varnos(), because this function would >recurse into T_RelabelType nodes. > Hmmm, yeah. I think you're right that's unnecessary. I misread the walker function, I think. >Also do we need to call bms_free(varnos) for each pathkey here to avoid >waste of memory? > I don't think so. It wouldn't hurt, but we don't do that for other pull_vernos calls either AFAICS. regards -- Tomas Vondra http://www.2ndQuadrant.com PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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