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virtualization

virtualization

Posted Mar 27, 2014 19:32 UTC (Thu) by marcH (subscriber, #57642)
In reply to: virtualization by kleptog
Parent article: PostgreSQL pain points

> > * Clobbering all other IO-using software on the same machine.

> For the second, as a userspace program you don't have a good view of what the rest of the system is doing, hence you might be interfering with other processes. The kernel has the overview.

How is the raw partition approach worse here? I would intuitively think it makes things better: less sharing.

Anyway: any database of serious size runs on dedicated or practically dedicated hardware, doesn't it?


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virtualization

Posted Mar 28, 2014 22:24 UTC (Fri) by kleptog (subscriber, #1183) [Link]

> > > * Clobbering all other IO-using software on the same machine.

> > For the second, as a userspace program you don't have a good view of what the rest of the system is doing, hence you might be interfering with other processes. The kernel has the overview.

> How is the raw partition approach worse here? I would intuitively think it makes things better: less sharing.

I think it depends on what your goals are. If your goal is to make the absolutely fastest database server possible, then you'd probably want to use raw access on a system with nothing else running.

If your goal is to make a database server that is broadly useful, runs efficiently on a wide variety of systems then asking the kernel to do its job is the better idea.

PostgreSQL tends to the latter. The gains you can get from raw access are simply not worth the effort and would make PostgreSQL much harder to deploy in many situations. A database server that only works well when it's got the machine to itself is a PITA in many situations.

virtualization

Posted Mar 29, 2014 3:37 UTC (Sat) by fandingo (guest, #67019) [Link]

> How is the raw partition approach worse here?

I'm not sure a database should be implementing operations necessary for ATA TRIM.


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