On Jul 1, 2007, at 11:36 AM, mc wrote:
> > Thanks. > > You say you are not a fan. What is the preferred way to solve the > problem I described? optimistically. i would ensure that appropriate constraints are placed upon the table such that two conflicting INSERT statements would result in one of them raising an exception; when the second client encounters this exception, it starts over again and re-SELECTs the row from the table. The case for the optimistic approach is one of "how often will a confict reasonably take place ?" I think conficts on INSERT, for all the use cases I can think of (such as inserting unique keywords), are exceedingly rare, since they correspond usually to end-user activities, where two users come up with the same new information at the exact same time. Even if you did have thousands of users hammering an application where many are expected to come up with the exact same information (such as, everyone is going to tag their photos with "kids" and "pets" which get added to a table of unique keywords), once a fair degree of all that "unique" data is inserted, then you'd no longer have conflicts, and the pessimistic locking would then add tremendous and almost always unnecessary latency to an applciation that has thousands of users hammering it. If I were running a really big website, id even try pre-populate the table with expected values before going live. on the other hand, if end users are not the issue, and you are instead writing an application that expects to have INSERT conflicts because it spawns a huge number of worker threads that are all operating upon the same data, locking the whole table for each INSERT will completely defeat the purpose of having worker threads, and you might as well not use them. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~----------~----~----~----~------~----~------~--~---
