> On 6 Jun 2019, at 22:40, Robert Haas <robertmh...@gmail.com> wrote:
> It looks to me as though any table AM that uses the relation forks > supported by PostgreSQL in a more or less normal manner is likely to > require an implementation of the relation_size callback that is > identical to the one for heap, and an implementation of the > estimate_rel_size method that is extremely similar to the one for > heap. The latter is especially troubling as the amount of code > duplication is non-trivial, and it's full of special hacks. Makes sense. Regarding one of the hacks: + * HACK: if the relation has never yet been vacuumed, use a minimum size + * estimate of 10 pages. The idea here is to avoid assuming a + * newly-created table is really small, even if it currently is, because + * that may not be true once some data gets loaded into it. When this is a generic function for AM’s, would it make sense to make the minimum estimate a passed in value rather than hardcoded at 10? I don’t have a case in mind, but I also don’t think that assumptions made for heap necessarily makes sense for all AM’s. Just thinking out loud. > Here is a patch that tries to improve the situation. I don't know > whether there is some better approach; this seemed like the obvious > thing to do. A small nitpick on the patch: + * estimate_rel_size callback, because it has a few additional paramters. s/paramters/parameters/ cheers ./daniel
