On Tue, 2008-04-22 at 17:50 -0400, Alvaro Herrera wrote: > Simon Riggs wrote: > > On Tue, 2008-04-22 at 15:49 -0400, Alvaro Herrera wrote: > > > > > - Three CopySnapshot call sites remain outside snapmgr.c: DoCopy() on > > > copy.c, ExplainOnePlan() on explain.c and _SPI_execute_plan() on spi.c. > > > They are there because they grab the current ActiveSnapshot, modify it, > > > and then use the resulting snapshot. There is no corresponding > > > FreeSnapshot, because it's not needed. > > > > Not needed? How can we be certain that the modified snapshot does not > > outlive its original source? > > It's not CopySnapshot that's not needed, but FreeSnapshot. The point > here is that the snapshot will be freed automatically as soon as it is > PopActiveSnapshot'd out of existance. CopySnapshot creates a new, > separate copy of the passed snapshot, and each of them will be freed > (separately) as soon as their refcounts reach zero.
OK, so it can;t be copied to a longer lived memory context? -- Simon Riggs 2ndQuadrant http://www.2ndQuadrant.com -- Sent via pgsql-patches mailing list (pgsql-patches@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-patches
