> > >> There's an advantage if we can combine stats across multiple relations > >> - we don't have to sample children twice when analyzing the parent > >> without ONLY. Instead we could produce parent statistics by combining > >> statistics across children and the parent. To me this looks like > >> altogether a different beast just like partial aggregates. > > > > > > I think this patch is only ever going to get us out of 1 of the 2 > samples, which isn't ideal but it is a savings. > > > > I am not suggesting to synthesize sample rows. Calculate the > statistics of the parent table from that of its children. >
I'm not sure we can actually do that. The functions that compute the statistics are all based off of row samples, not already computed statistics. I don't think we can synthesize a rowsample from the imported statistics, at least not accurately. If I'm misunderstanding what you're suggesting, please correct me. > The note just mentions partition table but the limitation applies to > any foreign child table. > Noted. Will fix in next revision.
