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.
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