Hello,

 

I pushed the logs to the DEBUG5 level with no luck.

 

So I decided to take a look at the code. 

Serialization conflict detection is done in 
src/backend/storage/lmgr/predicate.c, where transactions that are doomed to 
fail are marked as such with the SXACT_FLAG_DOOMED flag.

 

I simply added elog(NOTIFY,...) calls with the DEBUG1 level, each time the flag 
is set, compiled the code and give it a try.

 

The results are amazing for me, because this simple modification allows me to 
see which query is marking other running transactions to fail.

Without this information, this is really difficult to understand what's going 
on and, eventualy, modify my program to make my transactions run successfully 
more often.

 

What is the correct way to suggest this improvement for a future version of 
PostgreSQL ?

 

Regards.

 

Olivier.

 

De : pgsql-general-ow...@postgresql.org 
[mailto:pgsql-general-ow...@postgresql.org] De la part de Olivier MATROT
Envoyé : mardi 25 novembre 2014 13:00
À : pgsql-general@postgresql.org
Objet : [GENERAL] Serialization exception : Who else was involved?

 

I'm using PostgreSQL 9.2.8 on Windows x64.

 

When a transaction as SERIALIZABLE isolation level is failing, is there a way 
to know which connection(s), thus transaction(s), were involved in the overall 
process ?

 

I'm working on an accounting database. I know that we should retry the 
transaction, this is what we do. I've encountered an issue where a transaction 
has to be run 10 times to succeed on a busy system.

 

There should be a serious problem here. I'm wondering if there is a 
configuration parameter that would allow the system to tell in the exception 
detail the other connections involved in the failure.

 

The Postgresql wiki on SSI has no such information.

 

Thanks is advance.

 

Olivier.

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