On 12 November 2012 16:51, Robert Haas <robertmhaas@gmail.com> wrote:
> Although there may be some workloads that access very large numbers of
> tables repeatedly, I bet that's not typical.
Transactions with large numbers of DDL statements are typical at
upgrade (application or database release level) and the execution time
of those is critical to availability.
I'm guessing you mean large numbers of tables and accessing each one
multiple times?
> Rather, I bet that a
> session which accesses 10,000 tables is most likely to access them
> just once each - and right now we don't handle that case very well;
> this is not the first complaint about big relcaches causing problems.
pg_restore frequently accesses tables more than once as it runs, but
not more than a dozen times each, counting all types of DDL.
-- Simon Riggs http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services