On Feb 4, 2011, at 5:46 PM, Josh Stratton wrote: > I'm currently passing the table the sequence object, when I create the > table. I've been building the table with metadata.create_all. > > Calling sequnce.create() before creating the table complains of no > binding to an engine or a connection. I understand this makes sense > as I haven't told the sequence where to connect, but I don't see > anything in the docs for connecting the sequence to the > engine/connection. Is there a hidden parameter for binding?
All create() methods accept "bind" as an argument. While this general concept is described at http://www.sqlalchemy.org/docs/core/schema.html?highlight=sequence#creating-and-dropping-database-tables, that example is specific to the Table object, so it appears we need to add :members: to our Sphinx documentation for Sequence so that you can see that commonality without assuming. > Or if I > include this sequence in in the table, should that sequence be > associated with the metadata object I use to make the table? > > sequence = Sequence('id_seq', start=siteIndex, increment=len(sites)) > #sequence.create() > > table = Table('acounts', self.metadata, > Column(....)) > > self.metadata.create_all() > > > On Fri, Feb 4, 2011 at 1:46 PM, Michael Bayer <mike...@zzzcomputing.com> > wrote: >> The sequence has to be created (meaning, the appropriate DDL statements must >> be executed) on the target platform with those options, or the appropriate >> ALTER statements emitted to ALTER the sequence's settings. >> >> So when those flags are applied to sqlalchemy.Sequence(), its assumed that >> you're using table.create(), metadata.create_all(), or sequence.create() to >> issue the CREATE SEQUENCE call. The INCREMENT BY and START WITH clauses >> should be emitted as of the 0.6 series of SQLAlchemy. >> >> >> >> On Feb 4, 2011, at 2:10 PM, Josh Stratton wrote: >> >>> I'm connecting to an Oracle database for my work and we do replication >>> by periodically joining tables across sites instead of a single server >>> just in case a link in between goes down. One issue with this though >>> is I need to generate unique keys for a single table so if the >>> connection does go down, insertions to both tables won't cause a >>> conflict when it's time to merge. >>> >>> Because the ids aren't important to me during insertion, I just use a >>> Sequence object (since Oracle doesn't support autoincrementing). This >>> has worked fine, but I'm now trying how to combine this with the >>> unique keys across the two sites. I noticed the Sequence class has a >>> start and increment tag, which I thought would work perfectly by >>> interleaving the keys per site. >>> >>> For example... >>> >>> if site1: >>> init = 0 >>> else: >>> init = 1 >>> >>> sequence = Sequence('id_seq',start=init,increment=2) >>> >>> I don't see any actual documentation for what start and increment do >>> (http://www.sqlalchemy.org/docs/core/schema.html#sqlalchemy.schema.Sequence), >>> so I'm just assuming they function as I'd expect, where start is the >>> first id to try and increment is the space between the possible id's, >>> so site 1's ids will always be % 2 == 0, while site 2's would be % 2 >>> == 1. >>> >>> This doesn't seem to be what I'm getting however. In a few test cases >>> on one site, the first id starts at 10,283 and the next one generated >>> is 10,284. In this case it's starting at a crazy high value other >>> than 0 and it doesn't seem to be incrementing at all. Am I using >>> these flags incorrectly? Is this a bug in sqlalchemy? Deprecated >>> flags? Or is this whole idea garbage and I should use a guid? >>> >>> Thanks. >>> >>> -- >>> 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 >>> sqlalchemy+unsubscr...@googlegroups.com. >>> For more options, visit this group at >>> http://groups.google.com/group/sqlalchemy?hl=en. >>> >> >> -- >> 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 >> sqlalchemy+unsubscr...@googlegroups.com. >> For more options, visit this group at >> http://groups.google.com/group/sqlalchemy?hl=en. >> >> > > -- > 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 > sqlalchemy+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/sqlalchemy?hl=en. > -- 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 sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
