Hi, On 2019-04-22 14:17:48 -0400, Tom Lane wrote: > Andres Freund <and...@anarazel.de> writes: > > On 2019-04-22 13:27:17 -0400, Tom Lane wrote: > >> I wonder > >> also if it wouldn't be smart to explicitly check that the "guaranteeing" > >> column is not attisdropped. > > > Yea, that probably would be smart. I don't think there's an active > > problem, because we remove NOT NULL when deleting an attribute, but it > > seems good to be doubly sure / explain why that's safe: > > /* Remove any NOT NULL constraint the column may have */ > > attStruct->attnotnull = false; > > I'm a bit unsure whether to make it an assert, elog(ERROR) or just not > > assume column presence? > > I'd just make the code look like > > /* > * If it's NOT NULL then it must be present in every tuple, > * unless there's a "missing" entry that could provide a non-null > * value for it. Out of paranoia, also check !attisdropped. > */ > if (att->attnotnull && > !att->atthasmissing && > !att->attisdropped) > guaranteed_column_number = attnum; > > I don't think the extra check is so expensive as to be worth obsessing > over.
Oh, yea, the cost is irrelevant here - it's one-off work basically, and pales in comparison to the cost of JITing. I was more thinking about whether it's worth "escalating" the violation of assumptions. Greetings, Andres Freund
