Re: [Postgres-xc-general] JDBC driver for 0.9.4

[Lionel F. <lio...@gm...>]

Hello,

ran gtm with -x 1025, the same problem appears.
(ERROR:  prepared transaction with identifier "T1530" does not exist
STATEMENT:  COMMIT PREPARED 'T1530')

I'm shutting down autovacuum on nodes to see if problem persists (and
re-enable debug1 tracing)

Regards

Lionel F.


2011/6/7 Michael Paquier <mic...@gm...>

>
>
> On Mon, Jun 6, 2011 at 9:39 PM, Lionel Frachon <lio...@gm...>wrote:
>
>> Hello,
>>
>> looking at the debug1 mode log on datanode3, I found some interesting
>> points hereafter (vacuum on, max_prepared_transactions=5000):
>>
>> (with normal inserts)
>> [....]
>> DEBUG:  unset snapshot info
>> DEBUG:  global snapshot info: gxmin: 101, gxmax: 101, gxcnt: 0
>> DEBUG:  unset snapshot info
>> DEBUG:  global snapshot info: gxmin: 101, gxmax: 101, gxcnt: 0
>> DEBUG:  unset snapshot info
>> DEBUG:  [re]setting xid = 0, old_value = 0
>> DEBUG:  unset snapshot info
>> DEBUG:  Received new gxid 102
>> DEBUG:  [re]setting xid = 102, old_value = 0
>> DEBUG:  TransactionId = 102
>> DEBUG:  xid (102) does not follow ShmemVariableCache->nextXid (665)
>> DEBUG:  Record transaction commit 101
>> DEBUG:  Record transaction commit 102
>> DEBUG:  [re]setting xid = 0, old_value = 0
>> DEBUG:  unset snapshot info
>> DEBUG:  Received new gxid 103
>> DEBUG:  [re]setting xid = 103, old_value = 0
>> DEBUG:  unset snapshot info
>> DEBUG:  global snapshot info: gxmin: 103, gxmax: 103, gxcnt: 0
>> DEBUG:  TransactionId = 103
>> DEBUG:  xid (103) does not follow ShmemVariableCache->nextXid (665)
>> DEBUG:  unset snapshot info
>> DEBUG:  global snapshot info: gxmin: 103, gxmax: 103, gxcnt: 0
>>
>> While inserting with dsitrubuted hashed keys :
>>
>> [...]
>> DEBUG:  [re]setting xid = 0, old_value = 0
>> DEBUG:  unset snapshot info
>> DEBUG:  Received new gxid 522
>> DEBUG:  [re]setting xid = 522, old_value = 0
>> DEBUG:  TransactionId = 522
>> DEBUG:  xid (522) does not follow ShmemVariableCache->nextXid (665)
>> DEBUG:  Record transaction commit 521
>> DEBUG:  Record transaction commit 522
>> DEBUG:  [re]setting xid = 0, old_value = 0
>> DEBUG:  unset snapshot info
>> DEBUG:  Received new gxid 524
>> DEBUG:  [re]setting xid = 524, old_value = 0
>> ERROR:  prepared transaction with identifier "T523" does not exist
>> STATEMENT:  COMMIT PREPARED 'T523'
>> DEBUG:  [re]setting xid = 0, old_value = 524
>> DEBUG:  unset snapshot info
>> DEBUG:  Received new gxid 526
>> DEBUG:  [re]setting xid = 526, old_value = 0
>> ERROR:  prepared transaction with identifier "T525" does not exist
>> STATEMENT:  COMMIT PREPARED 'T525'
>> DEBUG:  [re]setting xid = 0, old_value = 526
>> DEBUG:  unset snapshot info
>> DEBUG:  Received new gxid 528
>> DEBUG:  [re]setting xid = 528, old_value = 0
>> ERROR:  prepared transaction with identifier "T527" does not exist
>> [...]
>>
> You are right.
> But this log:
>
> DEBUG:  Received new gxid 103
> means that GTM is feeding cluster in transaction ID to a very low value.
> This may lead to visibility problems.
> You should start GTM with an option like -x 1000 to be sure that it doesn't
> feed transaction IDs lower than 628.
> --
> Michael Paquier
> http://michael.otacoo.com
>