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? 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.
