On Tue, Mar 22, 2011 at 3:12 PM, Michael Bayer <[email protected]> wrote:
> if you say this:
>
> Table('sometable', MetaData(), autoload=True, autoload_with=some_engine)
>
> its not looking for "changes", its reflecting the entire form of that table
> brand new, each time. This because the MetaData() object is empty. If OTOH
> you were to call the"Table()" constructor multiple times with the same table
> name and the *same* MetaData object, nothing happens on the second try - the
> existing Table is used. The example code you had seems to be doing the
> former, reflecting each time on MetaData(). So it is calling "PRAGMA
> table_info(tablename)" each time.
>
> As far as why it fails in your specific case, I couldn't say for sure, but it
> seems possible that Migrate's practice of dropping the whole table, copying
> to a temp table, then copying back to the original table may be part of the
> problem. Perhaps the pysqlite or sqlite3 does not see the proper state when
> PRAGMA table_info() is used. Turning on echo='debug' would illustrate the
> full SQL conversation occurring with the SQLite database.
The test case executes the command `sqlite3
glance_test_migration.sqlite ".schema images"` directly after doing:
images_table = Table('images', MetaData(), autoload=True,
autoload_with=self.engine)
As you can see from the output of the test case, the images_table.c
contains different columns than what is output by the sqlite3 command.
That is why I think it's an SA problem and nothing to do with the
migrate script.
-jay
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