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
Experts in Analytics, Data Architecture and PostgreSQL
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