On Wed, Jun 8, 2016 at 9:40 AM, Kevin Grittner <kgri...@gmail.com> wrote: >>> Of course, ii_BrokenHotChain should be renamed to something like >>> ii_UnsafeForOldSnapshots, and some comments need to be updated; but >>> the above is the substance of it. >> >> I don't know why we'd want to rename it like that... > > If we made the above change, the old name would be misleading, but > I've thought better of that and attach a slightly different > approach (tested but not yet with comment adjustments); attached.
Kevin asked me to look at this patch, and maybe update it, but after some further study, I am not at all convinced that there's any actual bug here. Here's why: in order for the HeapTupleSatisfiesVacuum() in IndexBuildHeapRangeScan() to return HEAPTUPLE_DEAD instead of HEAPTUPLE_RECENTLY_DEAD, it would have to be using an OldestXmin value that doesn't include all of the snapshots in the system. But that will never happen, because that xmin comes directly from GetOldestXmin(heapRelation, true), which knows nothing about snapshot_too_old and will therefore never exclude any snapshots. If we were to pass the output of HeapTupleSatisfiesVacuum() through TransactionIdLimitedForOldSnapshots() before using it here, we would have a bug. But we don't do that. Do you have a test case that demonstrates a problem, or an explanation of why you think there is one? -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
