[ckan-dev] DB connection pooling

Fri Jan 31 13:53:49 UTC 2014

Hi list,

in a CKAN instance I am working on, I found a problem dealing with database 
disconnections (the DB is shut down every night for maintenance).
I guess that connection pooling would help mitigating the disconnections 
issue.

Referencing to this page
 http://docs.sqlalchemy.org/en/rel_0_7/core/pooling.html
I can see that SQLAlchemy offers quite a few parameters for configuring a 
connection pool when the engine is created.

Looking at how SQLAlchemy is initialized here
   https://github.com/ckan/ckan/blob/master/ckan/config/middleware.py#L344
it seems that in CKAN you can only configure SQLAlchemy with the connection URL 
(which is of course mandatory), but other parameters can not be specified. 

Am I missing any piece of code where the pool is instanced and configured?

If not, the idea is to open a pull request for a patch that reads optional 
properties from the ini file (e.g.: 
- sqlalchemy.pool_recycle
- sqlalchemy.pool_size
- sqlalchemy.max_overflow
- sqlalchemy.pool_timeout , ...)
and pass them as params to the sqlalchemy engine.

Any pointer to anything I'm missing?

   Thanks,
   Emanuele

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