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 <[email protected]> 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 >> -- >> 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 [email protected]. >> To post to this group, send email to [email protected]. >> Visit this group at http://groups.google.com/group/h2-database. >> For more options, visit https://groups.google.com/groups/opt_out. >> >> >> > > -- > You received this message because you are subscribed to a topic in the > Google Groups "H2 Database" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/h2-database/bGNuMpLr8IY/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/h2-database. > For more options, visit https://groups.google.com/groups/opt_out. > > > > > -- 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 [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/h2-database. For more options, visit https://groups.google.com/groups/opt_out.
