On 18 November 2017 at 17:12, Stuart McMillan <stum...@gmail.com> wrote:
> Noel,
>
> Yes - certainly the session locking (system or connection session) is one
> issue I have been wrestling with - especially when the CTE persistent views
> have to join the parent views lifecycle - I did a hacky-fix which I am not
> happy about to bypass that (and might not pass a code review).
>
there a couple of tricks we use in other places that might help.
(1) we tie the lifetime of stuff to the lifetime of the top-level
statement, not to the lifetime of the parent object. When dealing with
circular stuff, this helps
(2) when deleting these things, we use a loop that looks like
while (true)
progress = false
for each live object
progress |= try to delete object
if (!progress) break
>
> If we sidestep (ignore for the time being) my hacky attempts to bypass
> that issue - the next stumbling block was making the persistent views truly
> persistent - even across database reconnections. The blocker there is in
> reviving the cte views from their db persisted state - which fails dismally
> while using the plan SQL to re-create the cte views. I have to admit I was
> at a loss at how to fix that, since I do not understand the mechanism in
> which permanent DB-objects are persisted in H2. Which classes and fields
> are persisted in the db across connections/db-restarts for views and tables?
>
>
It's actually (mostly) simple. We just store the SQL required to re-create
each object, and then we re-parse and re-execute each chunk of SQL at
startup. There is a couple of stages to make this work, and some flags to
say things like "this is db init, do not try doing validation/compile/etc
yet"
And this all runs sequentially on the system session.
--
You received this message because you are subscribed to the Google Groups "H2
Database" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to h2-database+unsubscr...@googlegroups.com.
To post to this group, send email to h2-database@googlegroups.com.
Visit this group at https://groups.google.com/group/h2-database.
For more options, visit https://groups.google.com/d/optout.
