>> 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.
