On 04/06/2015 11:35 AM, Alvaro Herrera wrote: > Josh Berkus wrote: > >> I agree with Jim that if we have a trustworthy Frozen Map, having a >> ReadOnly flag is of marginal value, unless such a ReadOnly flag allowed >> us to skip updating the individual row XIDs entirely. I can think of >> some ways to do that, but they have severe tradeoffs. > > If you're thinking that the READ ONLY flag is only useful for freezing, > then yeah maybe it's of marginal value. But in the foreign key > constraint area, consider that you could have tables with > frequently-referenced PKs marked as READ ONLY -- then you don't need to > acquire row locks when inserting/updating rows in the referencing > tables. That might give you a good performance benefit that's not in > any way related to freezing, as well as reducing your multixact > consumption rate.
Hmmmm. Yeah, that would make it worthwhile, although it would be a fairly obscure bit of performance optimization for anyone not on this list ;-) -- Josh Berkus PostgreSQL Experts Inc. http://pgexperts.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
