On Fri, 2005-12-09 at 12:32 -0500, Tom Lane wrote: > Alvaro Herrera <[EMAIL PROTECTED]> writes: > > My proposal to solve that problem, is to make any transaction that > > inserts or modifies tuples in a table that is marked as frozen, unfreeze > > it first. The problem I had last time was finding a good spot in the > > code for doing so. I'm now proposing to do it in the parser, in > > setTargetTable(). > > My god, no. Do you have any idea how many paths for updates you've missed? > (Think about prepared plans for starters.) > > Furthermore, you can't do this in the way you propose (non-WAL-logged > update to pg_class). What if the system crashes without ever having > written this update to disk? The inserted tuples might have made it --- > whether they're committed or not doesn't matter, you've still blown it. > > I don't see any very good argument for allowing this mechanism to set > minxid = FrozenXid in the first place. If there are only frozenXid in > the table, set minxid = current XID. That eliminates the entire problem > at a stroke. > > (Yes, I know what you are going to say. The idea of freezing a table > and then never having to vacuum it at all is NOT worth the cost of > putting in a mechanism that would guarantee its safety.)
>From what's been said VACUUM FREEZE will not alter the fact that a frozen table will need vacuuming again in the future and so cannot ever be read-only. I can't really see any reason to run VACUUM FREEZE... If you want to make a table read-only forever, we need a separate command to do that, ISTM. ALTER TABLE ... READONLY could set minXid = FrozenTransactionId, indicating no further VACUUMs required, ever. We can then disallow INSERT/UPDATE/DELETE against the table in the permissions layer. Best Regards, Simon Riggs ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org