Hi Amit On 2021-Nov-16, Amit Langote wrote:
> AFAICS, MERGE operating on an inheritance parent that is not > partitioned should work mostly the same as the case where it is > partitioned (good thing that it works at all without needing any > special code!), though only the INSERT actions would have to be > handled appropriately by the user using triggers and such. And also I > guess any UPDATE actions that need to move rows between child tables > because that too involves tuple routing logic. As long as we're clear > on that in the documentation, I don't see why this case should not be > covered in the initial version. Yeah, I think the reason it works so cleanly is that the code you and/or Tom added to be able to get rid of inheritance_planner is superb, including the new row identity stuff. For the same reason, I suspect that adding support for foreign tables should be reasonably simple -- just add explicit support for handling "wholerow" in a few places. I have not tried. > I thought for a second about the cases where child tables have columns > not present in the root parent mentioned in the command, but I guess > that possibility doesn't present problems given that the command > wouldn't be able to mention such columns to begin with; it can only > refer to the root parent's column which must be present in all of the > affected child tables. Right. On the other hand, if we did have a problem with extra columns, ISTM that would be on the user's head, not our responsibility. In the example I added, there is one child table with variant column layout; it did require that the insertion trigger explicitly lists the columns in the INSERT statement for that table, but otherwise it work correctly. > In any case, I have a feeling that the planner would catch any > problematic cases if there're any while converting MergeAction > expressions into the individual child table layouts. Yeah, AFAICS it worked fine for the case I tried. Maybe there are more elaborate ones that I didn't think of, of course. -- Álvaro Herrera 39°49'30"S 73°17'W — https://www.EnterpriseDB.com/ "Puedes vivir sólo una vez, pero si lo haces bien, una vez es suficiente"
