Re: Optimize update query

Yeah, this area is changing very fast!

I agree - choosing carefully is important, as there are still plenty of
older models around that are substantially slower. Also choice of
motherboard chipset can strongly effect overall performance too. The 6
Gbit/s ports on Sandy and Ivy bridge Mobos [1] seem to get close to that
rated performance out of the SSD that I've tested (Crucial m4, Intel
various).

Cheers

Mark

[1] Which I think are actually Intel or Marvell controllers.

On 03/12/12 00:14, Vitalii Tymchyshyn wrote:
> Well, it seems that my data can be outdated, sorry for that. I've just
> checked performance numbers on Tom's hardware and it seems that best sad
> really do 500 MB/s. Some others do 100. So, I'd say one must choose wisely
> (as always :-) ).
>
> Best regards,
> Vitalii Tymchyshyn
> 1 груд. 2012 00:43, "Mark Kirkwood" <mark(dot)kirkwood(at)catalyst(dot)net(dot)nz> напис.
>
>> Hmm - not strictly true as stated: 1 SSD will typically do 500MB/s
>> sequential read/write. 1 HDD will be lucky to get a 1/3 that.
>>
>> We are looking at replacing 4 to 6 disk RAID10 arrays of HDD with a RAID1
>> pair of SSD, as they perform about the same for sequential work and vastly
>> better at random. Plus they only use 2x 2.5" slots (or, ahem 2x PCIe
>> sockets), so allow smaller form factor servers and save on power and
>> cooling.
>>
>> Cheers
>>
>> Mark
>>
>> On 30/11/12 23:07, Vitalii Tymchyshyn wrote:
>>
>>> Oh, yes. I don't imagine DB server without RAID+BBU :)
>>> When there is no BBU, SSD can be handy.
>>> But you know, SSD is worse in linear read/write than HDD.
>>>
>>> Best regards, Vitalii Tymchyshyn
>>>
>>>
>>> 2012/11/30 Mark Kirkwood <mark(dot)kirkwood(at)catalyst(dot)net(dot)nz
>>> <mailto:mark(dot)kirkwood(at)**catalyst(dot)net(dot)nz <mark(dot)kirkwood(at)catalyst(dot)net(dot)nz>>>
>>>
>>> Most modern SSD are much faster for fsync type operations than a
>>> spinning disk - similar performance to spinning disk + writeback
>>> raid controller + battery.
>>>
>>> However as you mention, they are great at random IO too, so Niels,
>>> it might be worth putting your postgres logs *and* data on the SSDs
>>> and retesting.
>>>
>>>