On 18/07/2011 9:37 AM, mdxxd wrote:
> CPU:
> *Will PostgreSQL benefit from using hyperthreading in i7 2600k CPU? Or will
> there be no noticeable performance change if I use i5 2500K CPU(i.e no HT,
> just 4 cores)?
On a typical desktop system, hard disk I/O is the limiting factor rather
than CPU, so I imagine you wouldn't see much difference between the two.
PostgreSQL can only use one CPU core (or thread on HT CPUs) per query.
If you run few big queries, dual core might even be enough. If you run
lots and lots of tiny queries, you might benefit from lots of CPUs.
Examine your usage on your current system - see pg_stat_activity - to
get some idea what your usage is like.
> *Will there be noticeable performance improvements if I OC my CPU from
> 3.3ghz/3.4ghz(with turbo bust to 3.7ghz/3.8ghz) to 4.5ghz?
Again, it depends on whether your queries are limited by hard disk or
CPU. If they're limited by hard disk access, it won't make much
difference at all.
> RAM:
> *Will there be noticeable performance improvements if I will use 16GB RAM
> over 8GB RAM? I know big servers uses at least 16GB(often 32GB).
Depends on how big your database is. You want your database and indexes
to fit entirely in RAM if possible. If it fits in 8GB but not in 16GB,
the difference will be absolutely enormous. If it fits in 8GB then you
won't see much difference going up to 16GB.
Check your current total database size, including indexes, and work out
how much RAM you need. Allow for growth.
See the user manual for how to get your database size. Do *NOT* just get
the size of the pg data directory.
> *Will there be noticeable change between CAS 9 and CAS 8/7? 1333mhz/1600mgz
> ddr3 ram?
Probably only if your database is fully cached in RAM and the queries
are moving lots of data rather than doing complex processing on smaller
amounts of data.
The usual rule of thumb on this list is that more RAM is better than
faster RAM, but I know Greg Smith's testing has found that RAM speed and
in particular how the CPU accesses the RAM does matter.
See his book "PostgreSQL high performance" for a bit more information.
> SSD:
> Different SSD excel in different areas. I know that for general PC usage, 4K
> Q1 random read/write is the most important.
> What is the most important for PT3(and PostgreSQL) usage? Random? sequel?
> 4K/8K/16K / 32K/ +? 4K-64Thrd? 4K QD4/QD16/QD32 ? etc ...
Most consumer quality SSDs will eat your data the first time you have a
power cut. Be careful to get one with a supercapacitor or battery
backup. See past mailing list discussion for which SSDs are safe.
If your database fits entirely in RAM and you don't write to it
especially fast you might not even need an SSD. A RAID 1 array of
reasonable hard drives might be quite good enough.
> *I will use windows 7(x64)
>
> Any other recommendations? (regards to hardware, I will look for tuning
> after i'll buy the computer).
In general, Pg is faster on linux.
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