On 11-11-20 05:47 AM, Cédric Villemain wrote:
> 2011/11/20 Steve Singer<ssinger at ca.afilias.info>:
>>
>> I  wonder out load if the slony remote worker needs to be in a
>> serializable transaction or if READ COMMITTED is good enough.
>>
>> I also wonder if making the remote listener threads explicit read only
>> transactions would help.
>
> if it is a read only transaction, then it is preferable to set it explicitely.
> If I well understood Heikki, it should remove 'pivot' situation. See
> http://wiki.postgresql.org/images/4/4f/SSI-PGConfEU2011.pdf (slide 22
> for the immediate suggestions)

The attached patch makes the remoteListener read only and seems to 
eliminate the pivot situations involving sl_event and sl_confirm.

Making the remote worker READ COMMITTED seemed to break things.

Maxim do you have a test environment that you can reproduce this 
situation in, does the attach patch help?



>
>>
>> The disorder tests against a 9.1 machine hit many of these read/write
>> dependencies in a test run.   Slony just retries things and it
>> eventually works but I can see how a 500,000 item batch means that you
>> might often encounter an issue before finishing a SYNC.
>>
>> My unverified guess is that changing this won't break slony but might
>> effect applications querying the slave that depend on the serializable
>> behaviour and maybe it should be a configuration parameter.
>>
>> There are two places in remote_worker.c where it places the local
>> connection to serializable.
>>
>>
>>
>>
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>>
>
>
>

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