followup: Model/DB synchronization (was: Migrations (was: ERXSQLHelper))
followup: Model/DB synchronization (was: Migrations (was: ERXSQLHelper))
- Subject: followup: Model/DB synchronization (was: Migrations (was: ERXSQLHelper))
- From: OC <email@hidden>
- Date: Tue, 13 Jan 2015 18:22:41 +0100
On 13. 1. 2015, at 16:26, OC <email@hidden> wrote:
> ... I believe I know that pretty well. My problems -- at the moment at least -- are
>
> (a) sometimes (so far in one sole case, which is luckily harmless, but I fear future) the EOAdaptorChannel describeModelWithTableNames API does not read the current schema properly (returning an empty entity for a table which is far from empty)
>
> Is there another, more reliable API which reads in the current schema? I've tried the migration API, and far as I can say, it does not read the current schema at all -- correct me if I am wrong, but it seems to me the migration API assumes the programmer already knows the current schema. That's not my case, I need to read it from the database.
>
> (b) I did not find a way to switch my isolation level and locking discipline. I can set them up using the JDBC connexion URL all right, but then they stick, and commands like
>
> ERXJDBCUtilities.executeUpdateScript(channel,'SET TRANSACTION ISOLATION LEVEL SERIALIZABLE, LOCKING PESSIMISTIC;')
>
> simply do not work at all. That's a problem, for my application runs read-committed/optimistic, but to change the schema FrontBase demands the appropriate transactions to be run serializable/pessimistic.
>
> Would migration solve this? Given my JDBC connexion URL specifies read-committed/optimistic, would migration automatically use serializable/pessimistic transaction for schema changes?
These two remain unsolved and I would still appreciate some insight.
On the other hand...
> (c) which reminds me, meantime I've bumped into another weird thing which I alas had not time to pursue in detail yet: if I connect serializable/pessimistic, I can change schema all right, but it seems some fetches (some of them only, nor all) do not work for some reason?!? ... ... ... if I connect serializable/pessimistic (making no other change anywhere, just changing the JDBC connexion URL), I'm getting "can't open channel" exceptions
... I have found the culprit here meantime, it was a well-hidden typo in the pessimistic-mode URL (and one very strangely reported at that!) Anyway, it works now all right.
Thanks and all the best,
OC
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