[Zope] Zope 2.7.0 and custom_zodb.py

[Chris Withers]

John E. Barham wrote:
> Relational database connections are distributed from the general database
> connection pool.  See:
> http://www.zope.org/Members/petrilli/ZSQLFAQ

That article is old, unclear and misleading.

The relationship between connections to a relational database and the DA object 
isn't as rigid as Chris implies. Take, for example, my branch of the ZOracleDA 
adapter, which has it's own pool of Oracle connections that it shares across all 
DA instances.

> Elsewhere it's recommended that the database connection pool size be larger
> than the thread pool size.

Where and why?

There's no benefit in having more database connections that publisher threads, 
unless the publisher is leaking database connections, which it doesn't and 
usually doesn't...

Just occurred to me that you may be misunderstanding what a "database 
connection" is, since the zope terminology is horribly confused.

The "SQL Connection" object you add through the ZMI is NOT a database 
connection, either relational or ZODB, and the number of those objects has 
nothing to do with the zodb pool size and not much to do with the number of 
connections from Zope to your relational database.

BTW, what relational database and what database adapter are you using?

Chris

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