Re: SSI patch version 12 - Mailing list pgsql-hackers

From Kevin Grittner
Subject Re: SSI patch version 12
Date
Msg-id 4D35A5F40200002500039762@gw.wicourts.gov
Whole thread Raw
In response to Re: SSI patch version 12  ("Kevin Grittner" <Kevin.Grittner@wicourts.gov>)
List pgsql-hackers
"Kevin Grittner" <Kevin.Grittner@wicourts.gov> wrote:
> If my back-of-the-envelope math is right, a carefully constructed
> pessimal load could need up to (max_connections / 2)^2 -- so 100
> connections could conceivably require 2500 structures, although
> such a scenario would be hard to create.  Current "picked from
> thin air" numbers would have space for 500.
Er, actually, we would have space for 5000, because it's five times
the number of SERIALIZABLEXACT structures which is ten times
max_connections. I guess that would explain why I've never seen a
report of a problem.
Still, someone who creates a very large number of connections and
pounds them heavily with SERIALIZABLE transactions might conceivably
run into it.  Since that's something the docs explicitly warn you
*not* to do with serializable transactions, I'm not sure we need to
do more than make sure the error message and hint are good. 
Thoughts?
-Kevin


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