On Tue, May 04, 2004 at 11:21:18PM -0400, Bruce Momjian wrote: > Alvaro Herrera wrote:
> > I've whacked the subtrans patch enough so that the simple tests (i.e. > > non concurrent) for tuple visibility work. I can create a table and > > populate it in subtransactions, rollback or commit them selectively and > > get the desired effect at the end. Naturally, catalog entries also > > behave [somewhat] sanely. Oh, I made pg_subtrans work too. (Though > > whether it's relatively bug-free is yet to be proven.) > > I remember going through this. Other backends will use pg_subtrans to > know what transactions are in progress. They have to do the standard > lookups to find the status of the parent transaction. The backend-local > list of xids is needed so the commit can clean up those subtransaction > xids so that later transactions don't have to use pg_subtrans. Ok, this can be done with what I have so far. I'm not sure how slow will it be compared to checking the PGPROC struct, because it may involve getting a pg_subtrans page from disk. Currently I have 8 pg_subtrans buffers on shared memory, the same as pg_clog; maybe we want more to reduce that probability. 8 kB each, 2k xacts each, 16k xacts total. I'll test this and will probably be submitting a patch shortly. > Sorry I haven't gotten your patches in yet. Tom is working on some > other back patches. I've been sloppy lately with #ifdef, because it takes some time to get right and testing it takes even more time. I don't know if it's worth it -- do you still have the idea of incremental, non disturbing patches? > Also, do you have a plan to handle some of the more complex issues > like locking in subtransactions? Certainly. As soon as I have a concurrent scenario working, I'll pursue the cleanup of all modules at subxact abort. (I have some working, some which I know don't work, and some which I haven't tried yet.) -- Alvaro Herrera (<alvherre[a]dcc.uchile.cl>) "Cada quien es cada cual y baja las escaleras como quiere" (JMSerrat) ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster
