On Thu, Jun 12, 2014 at 01:40:59PM +0200, Andres Freund wrote: > Hi Tom, > > On 2014-06-06 15:44:25 -0400, Tom Lane wrote: > > I figured it'd be easy enough to get a better estimate by adding another > > counter to count just LIVE and INSERT_IN_PROGRESS tuples (thus effectively > > assuming that in-progress inserts and deletes will both commit). > > Did you plan to backpatch that? My inclination would be no... > > > I did > > that, and found that it helped Tim's test case not at all :-(. A bit of > > sleuthing revealed that HeapTupleSatisfiesVacuum actually returns > > INSERT_IN_PROGRESS for any tuple whose xmin isn't committed, regardless of > > whether the transaction has since marked it for deletion: > > > > /* > > * It'd be possible to discern between INSERT/DELETE in progress > > * here by looking at xmax - but that doesn't seem beneficial > > for > > * the majority of callers and even detrimental for some. We'd > > * rather have callers look at/wait for xmin than xmax. It's > > * always correct to return INSERT_IN_PROGRESS because that's > > * what's happening from the view of other backends. > > */ > > return HEAPTUPLE_INSERT_IN_PROGRESS; > > > > It did not use to blow this question off: back around 8.3 you got > > DELETE_IN_PROGRESS if the tuple had a delete pending. I think we need > > less laziness + fuzzy thinking here. Maybe we should have a separate > > HEAPTUPLE_INSERT_AND_DELETE_IN_PROGRESS result code? Is it *really* > > the case that callers other than VACUUM itself are okay with failing > > to make this distinction? I'm dubious: there are very few if any > > callers that treat the INSERT and DELETE cases exactly alike. > > My current position on this is that we should leave the code as is <9.4 > and HEAPTUPLE_INSERT_IN_PROGRESS for the 9.4/master. Would you be ok > with that? The second best thing imo would be to discern and return > HEAPTUPLE_INSERT_IN_PROGRESS/HEAPTUPLE_DELETE_IN_PROGRESS for the > respective cases. > Which way would you like to go?
Did we ever come to a conclusion on this? -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + Everyone has their own god. + -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
