Re: Vacuum: allow usage of more than 1GB of work mem

On 9/4/16 1:46 AM, Simon Riggs wrote:
>> > The patch also makes vacuum free the dead_tuples before starting
>> > truncation. It didn't seem necessary to hold onto it beyond that
>> > point, and it might help give the OS more cache, especially if work
>> > mem is configured very high to avoid multiple index scans.
> How long does that part ever take? Is there any substantial gain from this?

If you're asking about how long the dealloc takes, we're going to have 
to pay that cost anyway when the context gets destroyed/reset, no? Doing 
that sooner rather than later certainly seems like a good idea since 
we've seen that truncation can take quite some time. Might as well give 
the memory back to the OS ASAP.
-- 
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
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