exarkun at divmod.com
Thu Oct 27 18:30:26 CEST 2005
On Fri, 28 Oct 2005 00:17:54 +0800, "Neville C. Dempsey" <nevillednz.python at 3ttechnology.com> wrote:
>Why does this python program fail to read record "6000000"?
>import bsddb # twiceopen.py
>list1[key]="we have the technology"
>#print "key:",key,"val:",list2[key] # doesn't work...
>print "first:",list2.first() # also fails first time...
>Maybe the solution needs one of:
You really want to use transactions if you are going to access a database concurrently. So that means DB_INIT_TXN. Now since you need transactions, you need an environment, so you want to let bsddb create whatever environment files it needs. So that means DB_CREATE. Now since there's an environment, every process but the first to open it needs to *join* it, rather than opening it in the usual way. So that means DB_JOINENV for all but the first open call.
Except I don't think btopen() supports half these operations. You really want to use bsddb.db.DBEnv and bsddb.DB. Or a library that wraps them more sensibly: <http://divmod.org/users/viewcvs.twistd/trunk/atop/store.py?rev=9302&view=markup>. You probably don't want everything there, but the DatabaseEnvironment class (and supporting code) should be useful.
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