Re: FOR SHARE vs FOR UPDATE locks
От | Joshua D. Drake |
---|---|
Тема | Re: FOR SHARE vs FOR UPDATE locks |
Дата | |
Msg-id | 1164999278.29643.46.camel@localhost.localdomain обсуждение исходный текст |
Ответ на | Re: FOR SHARE vs FOR UPDATE locks (Tom Lane <tgl@sss.pgh.pa.us>) |
Список | pgsql-hackers |
On Fri, 2006-12-01 at 13:46 -0500, Tom Lane wrote: > "Heikki Linnakangas" <heikki@enterprisedb.com> writes: > > Let's throw an error for now. We have to come back to this in 8.3, I think. > > After further thought I think we should also seriously consider plan C: > do nothing for now. We now realize that there have been related bugs > since 8.0, namely that > > begin; > select some rows for update; > savepoint x; > update the same rows; > rollback to x; > > leaves the tuple(s) not locked. The lack of complaints about this from > the field suggests that this isn't a huge problem in practice. If we > do make it throw an error I'm afraid that we will break applications > that aren't having a problem at the moment. > > I'm also realizing that a fix along the throw-an-error line is > nontrivial, eg, HeapTupleSatisfiesUpdate would need another return code. > > So at this point we are facing three options: > - throw in a large and poorly tested "fix" at the last moment; > - postpone 8.2 until we can think of a real fix, which might > be a major undertaking; > - ship 8.2 with the same behavior 8.0 and 8.1 had. > None of these are very attractive, but I'm starting to think the last > is the least bad. /me struggles... IMHO: option 2 is the correct option, but the least favorable. option 1 is probably bad option 3 is the lesser of the evils if we document it loudly. Joshua D. Drake > > regards, tom lane > > ---------------------------(end of broadcast)--------------------------- > TIP 5: don't forget to increase your free space map settings > -- === The PostgreSQL Company: Command Prompt, Inc. === Sales/Support: +1.503.667.4564 || 24x7/Emergency: +1.800.492.2240 Providing the most comprehensive PostgreSQL solutions since 1997 http://www.commandprompt.com/ Donate to the PostgreSQL Project: http://www.postgresql.org/about/donate
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