Mark Dilger <hornschnor...@gmail.com> writes: > On 11/23/19 8:34 AM, Tom Lane wrote: >> It suddenly strikes me to worry that we have an XID wraparound hazard >> for entries in the notify queue.
> Is it worth checking for this condition in autovacuum? Dunno, maybe. It's a different avenue to consider, at least. > There shouldn't be too much reason to back-patch any of this, since > the change in 51004c717 only applies to v13 and onward. Or do you > see the risk you described as "pretty minimal" as still being large > enough to outweigh the risk of anything we might back-patch? There may not be a risk large enough to worry about before 51004c717, assuming that we discount cases like a single session staying idle-in-transaction for long enough for the XID counter to wrap (which'd cause problems for more than just LISTEN/NOTIFY). I haven't analyzed this carefully enough to be sure. We'd have to consider that, as well as the complexity of whatever fix we choose for HEAD, while deciding if we need a back-patch. regards, tom lane