Excerpts from Noah Misch's message of lun ene 02 16:25:25 -0300 2012: > On Mon, Jan 02, 2012 at 06:41:31PM +0000, Simon Riggs wrote: > > On Mon, Jan 2, 2012 at 6:06 PM, Noah Misch <n...@leadboat.com> wrote: > > > On Mon, Jan 02, 2012 at 05:09:16PM +0000, Simon Riggs wrote: > > >> Attached patch makes SnapshotNow into an MVCC snapshot, initialised at > > >> the start of each scan iff SnapshotNow is passed as the scan's > > >> snapshot. It's fairly brief but seems to do the trick. > > > > > > That's a neat trick. ?However, if you start a new SnapshotNow scan while > > > one is > > > ongoing, the primordial scan's snapshot will change mid-stream. > > > > Do we ever do that? (and if so, Why?!? or perhaps just Where?) > > I hacked up your patch a bit, as attached, to emit a WARNING for any nested > use of SnapshotNow. This made 97/127 test files fail. As one example, > RelationBuildRuleLock() does TextDatumGetCString() for every tuple of its > SnapshotNow scan. That may need a detoast, which itself runs a scan.
Uh, I thought detoasting had its own visibility test function .. I mean, otherwise, what is HeapTupleSatisfiesToast for? -- Álvaro Herrera <alvhe...@commandprompt.com> The PostgreSQL Company - Command Prompt, Inc. PostgreSQL Replication, Consulting, Custom Development, 24x7 support -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
