RE: [SQL] prob with aggregate and group by - returns multiples

From: George Dau <gedau(at)isa(dot)mim(dot)com(dot)au>
To: "'pgsql-sql(at)postgresql(dot)org'" <pgsql-sql(at)postgresql(dot)org>
Subject: RE: [SQL] prob with aggregate and group by - returns multiples
Date: 2000-02-28 21:58:24
Message-ID: 69D6F577E4ADD311ABE600805FFE80580EBCFB@isaexch.isa.mim.com.au
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The selects below are self-contained. The one that is failing is, in full,
#!/bin/bash
#
psql web <<EOS

select count(site), site
from hits
group by site;

\q;
EOS

The first part of the output is:
count|site
-----+-------------------------------
8|1.digital.cnet.com
18|1000.stars.ru
1|10e2.linkexchange.ru
2|128.11.10.58
1|192.148.121.27
1|195.115.59.156
7|195.172.106.37
1|195.86.97.21

and then, finally,
2|xbase.plugsys.com
3|xbase.plugsys.com
2|xbase.plugsys.com
1|xbase.plugsys.com
2|xlink.zdnet.com
2|xlink.zdnet.com
1|xlink.zdnet.com
2|xlink.zdnet.com
2|xlink.zdnet.com
2|xlink.zdnet.com
3|xlink.zdnet.com
2|xlink.zdnet.com
3|xlink.zdnet.com
2|xlink.zdnet.com
1|xlink.zdnet.com
1|y0.extreme-dm.com
1|y0.extreme-dm.com
2|y1.extreme-dm.com
1|yahoo.com.au
1|yellowpages.com.au
2|z0.extreme-dm.com
1|z0.extreme-dm.com
2|z1.extreme-dm.com
2|z1.extreme-dm.com
1|z1.extreme-dm.com
(5510 rows)

I have postgresql version 6.2 running on RedHat Linux kernel 2.2.5 The box
has 128Meg RAM
and lotsa disk. Upgrading to 6.5 will be either expensive (download) or very
slow (buy CD
from Canada). I hope there is another solution.

The TEMP table references are in HTML doco in query.html where it describes
"select into".

-----Original Message-----
From: Tom Lane [mailto:tgl(at)sss(dot)pgh(dot)pa(dot)us]
Sent: Monday, 28 February 2000 17:50
To: George Dau
Cc: 'pgsql-sql(at)postgresql(dot)org'
Subject: Re: [SQL] prob with aggregate and group by - returns multiples

George Dau <gedau(at)isa(dot)mim(dot)com(dot)au> writes:
> select count(site), site from hits group by site;

> The output contains lines like the following. Note that these are all
> consecutive in the output.

> 2|xlink.zdnet.com
> 2|xlink.zdnet.com
> 1|xlink.zdnet.com
> 2|xlink.zdnet.com
> 2|xlink.zdnet.com
> 2|xlink.zdnet.com
> 3|xlink.zdnet.com
> 2|xlink.zdnet.com
> 3|xlink.zdnet.com
> 2|xlink.zdnet.com
> 1|xlink.zdnet.com

> Suspecting that there were differences in each xlink.zdnet.com, I counted
> just them:

> web=> select count (*) from hits where site='xlink.zdnet.com';
> count
> -----
> 22
> (1 row)

> So, all 22 xlink.zdnet.com are selected above, but they have not grouped
in
> the previous one. Any ideas why?

Wow, that is bizarre. My first thought was that you had varying numbers
of trailing blanks in the "site" values, but your second example seems
to disprove that theory.

What Postgres version are you running, and on what platform? Can you
generate a self-contained example (a script that demonstrates the error
from a standing start)? I suspect you may be hitting a platform-
specific porting problem, but it's just speculation unless we have a
self-contained test case to try on other machines.

> On a lesser note: I tried "select * into temp from hits" as per the doco,
> but it barfs.

Postgres thinks that TEMP is a keyword, so it won't take it as a table
name unless you put quotes around it. If we have doco examples that
use TEMP as a table name, they need to be changed --- do you recall
where you saw that, exactly?

regards, tom lane

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