From: | "Michael Guyver" <kenevel(at)googlemail(dot)com> |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: Concatenate performance question |
Date: | 2006-12-06 19:56:46 |
Message-ID: | 30b57570612061156u4a6a0a7fjef1469819ee46be6@mail.gmail.com |
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Lists: | pgsql-general |
On 03/12/06, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> "Michael Guyver" <kenevel(at)googlemail(dot)com> writes:
> > ... Running the array_append version is faster by at least one order of
> > magnitude in these examples.
>
> Really? I see only about a 50% advantage (155 msec vs 105 msec) in both
> 8.1 and 8.2. What PG version are you running? What database encoding
> are you using?
Hi Tom,
Thanks for taking the time to have a look at this. Perhaps I
overstated the case when I said an order of magnitude :¬O That said,
however, I'm fairly sure that the difference was more than you've
seen.
The hardware may indeed have been a factor - I was running psql 8.1 on
a laptop (AMD 64 3200, 1GB RAM, 5400rpm HDD) so the difference in
performance may have been more pronounced. I will check the figures
when I next get to my laptop at home, but I'm currently doing silly
hours at work for the release we have this week.
From some fairly unscientific bodging I've found that a mixture of the
two is the most performant, as I mentioned in a previous post.
Incidentally using a RETURN NEXT statement where I previously employed
an array_append performed as well if not slightly better than my
previous approach. Any thoughts?
Cheers
Michael
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