Hi Thomas,
Thanks for the reply.
On 21/11/2013 6:43 AM, Thomas Mueller wrote:
>Does H2 implement Serializable Snapshot
Currently not, and I didn't plan to support it. In theory, it could be
supported with the MVStore, but I don't currently think it's very
important.
How does SERIALIZABLE isolation in MVCC mode compare to
SERIALIZABLE_SNAPSHOT? Aren't they the same thing?
Thanks,
Gili
Regards,
Thomas
On Sat, Aug 24, 2013 at 8:10 PM, Gili <cow...@bbs.darktech.org
<mailto:cow...@bbs.darktech.org>> wrote:
Thomas,
Can you please clarify how H2's implementation of MVCC interacts
with Transaction Isolation?
1. Is there a practical difference between READ_COMMITTED and
REPEATABLE_READ in MVCC mode? Doesn't MVCC prevent
READ_COMMITTED from seeing updates committed by other
transactions (after the current transaction has already read
the row once)? If so, aren't they identical?
2. Same question for REPEATABLE_READ and SERIALIZABLE isolation
in MVCC mode.
3. Does H2 implement
http://en.wikipedia.org/wiki/Serializable_Snapshot_Isolation#Serializable_Snapshot_Isolation
for
MVCC? If not, do you plan on doing so in the future?
Thank you,
Gili
On Sunday, June 23, 2013 11:23:16 AM UTC-4, Gili wrote:
Thanks Thomas. So you're saying I can use other isolation
modes with MVCC as I normally would?
Gili
On 23/06/2013 7:39 AM, Thomas Mueller wrote:
Hi,
H2 only supports row level locks when using the MVCC mode. By
the way, the plan is that in the future (with the MVStore),
the MVCC mode will be the default mode.
Insert/delete operations don't wait for other operations that
do not conflict. They wait for conflicting operations
(changes on the same rows).
> What happens in the following scenario?
H2 uses "read committed" by default, so T1 will see the value
from T2.
Regards,
Thomas
On Thu, Jun 20, 2013 at 8:18 PM, Gili
<cow...@bbs.darktech.org <mailto:cow...@bbs.darktech.org>> wrote:
Hi,
Looking at http://www.h2database.com/html/advanced.html#mvcc,
1. Does H2 only support table locks or MVCC? Or is there
a way to get row locks without MVCC?
2. Using MVCC, do insert/delete operations wait until
all open transactions complete?
3. Does this imply that open transactions will never
experience insert/delete rows by other threads in
mid-transaction?
4. What happens in the following scenario?
Database contains a single row: count[value=1]
T1: Open transaction
T2: Open transaction
T2: update count set value=2 where value=1
T2: commit
T1: select value from count
Will T1 see a value of 1 or 2?
Thanks,
Gili
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