Thread: Slow Index Creation, why is it not consuming more memory.
Just trying to figure something out.
9.3.4, CentOS6.5
256GB Ram
Maintenance_work_mem = 125GB
Effective_Cache = 65GB
I have 2 indexes running, started at the same time, they are not small and one will take 7 hours to complete.
I see almost zero disk access, very minor, not what I want to see when I have an index that will be as large as it is! , but whatever.
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
18059 postgres 20 0 5119m 2.4g 20m R 100.0 0.9 12:31.05 postmaster
18091 postgres 20 0 9794m 6.9g 20m R 100.0 2.7 11:41.61 postmaster
Why are 2 index using different amounts of resident mem, when they have the keys to the castle, and why are they not taking more?
I've tried this with as low as 4GB of maintenance_work_mem and the numbers in TOP stay the same.
Work_mem is 7GB.
What am I not understanding missing?
Thanks
Tory
On Mon, Dec 7, 2015 at 10:36 PM, Tory M Blue <tmblue@gmail.com> wrote: > What am I not understanding missing? Yes. There is a hard limit on the number of tuples than can be sorted in memory prior to PostgreSQL 9.4. It's also the case that very large work_mem or maintenance_work_mem settings are unlikely to help unless they result in a fully internal sort. There is evidence that the heap that tuple sorting uses benefits from *lower* settings. Sometimes as low as 64MB. We're working to make this better in 9.6. -- Regards, Peter Geoghegan