Обсуждение: RE: pre-beta is slow
> recently I have downloaded a pre-beta postgresql, I found > insert and update speed is slower then 7.0.3, > even I turn of sync flag, it is still slow than 7.0, why? > how can I make it faster? Try to compare 7.0.3 & 7.1beta in multi-user environment. Vadim
"Mikheev, Vadim" wrote: > > > recently I have downloaded a pre-beta postgresql, I found > > insert and update speed is slower then 7.0.3, > > even I turn of sync flag, it is still slow than 7.0, why? How much slower do you see it to be ? > > how can I make it faster? > > Try to compare 7.0.3 & 7.1beta in multi-user environment. As I understand it you claim it to be faster in multi-user environment ? Could you give some brief technical background why is it so and why must it make single-user slower ? --------------- Hannu
> > Try to compare 7.0.3 & 7.1beta in multi-user environment. > > As I understand it you claim it to be faster in multi-user > environment ? > > Could you give some brief technical background why is it so > and why must it make single-user slower ? Because of commit in 7.1 does fsync, with ot without -F (we can discuss and change this), but in multi-user env a number of commits can be made with single fsync. Seems I've described this before? Vadim
"Mikheev, Vadim" <vmikheev@SECTORBASE.COM> writes:
> Because of commit in 7.1 does fsync, with ot without -F
> (we can discuss and change this), but in multi-user env
> a number of commits can be made with single fsync.
I was planning to ask why you disabled the -F switch. Seems to me that
people who trusted their OS+hardware before would still want to do so
in 7.1, and so it still makes sense to be able to suppress the fsync
calls.
regards, tom lane
> > Because of commit in 7.1 does fsync, with ot without -F > > (we can discuss and change this), but in multi-user env > > a number of commits can be made with single fsync. > > I was planning to ask why you disabled the -F switch. Seems > to me that people who trusted their OS+hardware before would > still want to do so in 7.1, and so it still makes sense to be > able to suppress the fsync calls. I just didn't care about -F functionality, sorry. I agreed that we should resurrect it. Vadim
> > > Try to compare 7.0.3 & 7.1beta in multi-user environment. > > > > As I understand it you claim it to be faster in multi-user > > environment ? > > > > Could you give some brief technical background why is it so > > and why must it make single-user slower ? > > Because of commit in 7.1 does fsync, with ot without -F > (we can discuss and change this), but in multi-user env > a number of commits can be made with single fsync. > Seems I've described this before? Ops, I forgot to answer question "why in single-user env 7.1 is slower than 7.0.3?". I assumed that 7.1 was compared with 7.0.3 *with -F*, which probably is not correct, I don't know. Well, the next test shows that 7.1 is faster in single-user env than 7.0.3 *without -F*: table (i int, t text); 1000 INSERTs (in separate transactions), sizeof(t) 1 .. 256: 7.0.3: 42 sec -> 24 tps 7.1 : 24 sec -> 42 tps Vadim
> > I just didn't care about -F functionality, sorry. > > I agreed that we should resurrect it. > > OK. Do you want to work on that, or shall I? In near future I'll be busy doing CRC + "physical log" things... Vadim
"Mikheev, Vadim" <vmikheev@SECTORBASE.COM> writes:
> I just didn't care about -F functionality, sorry.
> I agreed that we should resurrect it.
OK. Do you want to work on that, or shall I?
regards, tom lane