On 12/07/2016 09:58 AM, John R Pierce wrote:
> On 12/7/2016 8:47 AM, Rob Sargent wrote:
>> Please tell me that in this case, updating 2 (big)integer columns
>> does not generate dead tuples (i.e. does not involve a insert/delete
>> pair).
>
> if the fields being updated aren't indexed, and there's free tuple
> space that has already been vacuumed in the same block, then the
> update is done via "HOT" (or is it HEAT?) within the same block... but
> with 1000s of updates per second to the same 500 rows ? odds of
> autovacuum keeping up are sketchy.. otherwise, all updates are
> insert/delete operations due to the requirements of MVCC
How does your reply change, if at all, if:
- Fields not index
- 5000 hot records per 100K records (millions of records total)
- A dozen machines writing 1 update per 10 seconds (one machine
writing every 2 mins)
- - each to a different "5000"
or (two modes of operation)
- - each to same "5000"
My guess this would be slow enough even in the second mode? Or at this
rate and style should I care?
Sorry for taking this off from OP's point