Hi,
I guess this could be improved, but it might be complicated; I didn't try
and don't plan to try.
The "automatic mixed mode" has some limits. It is not possible to
automatically re-run the complete transaction (multiple statements) because
the statements could depend on each other. The most logical way for an
application is to use a loop like this (pseudo-code, with connection pool):
repeat maxRetries
c = getConnection
c.execute "..."
c.execute "..."
c.commit
finally
c.close
Regards,
Thomas
On Mon, Sep 28, 2015 at 10:08 AM, Joonas Pulakka <[email protected]>
wrote:
> To elaborete,
>
> I do realize that if the first (server) process shuts down *during*
> incomplete transaction, then obviously that has to trigger an exception in
> the client because the transaction could not be completed, and even if a
> server would be re-started at that point, it would be probably difficult to
> guarantee ACID properties of the transaction.
>
> But I don't understand why there is an exception even if the transaction
> is started way *after* the first (server) process has shut down -
> couldn't the client just start a server in that case? Is this just a corner
> case that happens to be handled the way it is handled currently, or is
> there a specific reason why is has to be handled that way?
>
> Best Regards,
> Joonas
>
>
> perjantai 25. syyskuuta 2015 13.37.15 UTC+3 Joonas Pulakka kirjoitti:
>>
>> From http://h2database.com/html/features.html#auto_mixed_mode and
>> http://h2database.com/html/features.html#auto_reconnect :
>>
>> - (Mixed mode) When the first connection is closed, the server stops.
>> If other (remote) connections are still open, one of them will then start
>> a
>> server (auto-reconnect is enabled automatically).
>> - The auto-reconnect feature causes the JDBC driver to reconnect to
>> the database if the connection is lost. The automatic re-connect only
>> occurs when auto-commit is enabled; if auto-commit is disabled, an
>> exception is thrown.
>>
>> So this means that when mixed mode is used with auto-commits disabled,
>> and the first (server) process shuts down, then the second (client) process
>> throws an exception when processing the next statement, instead of
>> re-connecting to the DB. Furthermore (result of experimentation) it
>> *does* reconnect to the DB just by retrying the statement that threw the
>> exception. After that everything works fine again. Only the first statement
>> that's issued after the server died, receives Connection is broken:
>> "session closed" [90067-185];; Error code: 90067.
>>
>>
>> Question: what's the point of *automatic re-connect only occurs when
>> auto-commit is enabled; if auto-commit is disabled, an exception is thrown*?
>> Does this mean that if I want to use mixed mode with auto-commits disabled,
>> I have to make all my transactions to check for "session closed" exception
>> and retry in that case? Is there a better way?
>>
>>
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