Re: Freeze avoidance of very large table.

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