Обсуждение: How to split a table?

Felix Zhang <felix.zhang.2005@gmail.com> schrieb:

> Hi,
>
> I want to split a table to 2 small tables. The 1st one contains 60% records
> which are randomly selected from the source table.
> How to do it?

Why do you want to do this?


Andreas
--
Really, I'm not out to destroy Microsoft. That will just be a completely
unintentional side effect.                              (Linus Torvalds)
"If I was god, I would recompile penguin with --enable-fly."    (unknow)
Kaufbach, Saxony, Germany, Europe.              N 51.05082°, E 13.56889°

Perhaps something like:

CREATE TABLE foo2 AS SELECT * FROM foo WHERE (rand() <= 0.60);

?

HTH,

Greg Williamson
DBA
GlobeXplorer LLC


-----Original Message-----
From:    pgsql-sql-owner@postgresql.org on behalf of Andreas Kretschmer
Sent:    Tue 10/17/2006 1:34 AM
To:    pgsql-general@postgresql.org; pgsql-sql@postgresql.org; pgsql-novice@postgresql.org
Cc:
Subject:    Re: [SQL] [GENERAL] How to split a table?

Felix Zhang <felix.zhang.2005@gmail.com> schrieb:

> Hi,
>
> I want to split a table to 2 small tables. The 1st one contains 60% records
> which are randomly selected from the source table.
> How to do it?

Why do you want to do this?


Andreas
--
Really, I'm not out to destroy Microsoft. That will just be a completely
unintentional side effect.                              (Linus Torvalds)
"If I was god, I would recompile penguin with --enable-fly."    (unknow)
Kaufbach, Saxony, Germany, Europe.              N 51.05082°, E 13.56889°

---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
       choose an index scan if your joining column's datatypes do not
       match


-------------------------------------------------------
Click link below if it is SPAM gsw@globexplorer.com

"https://mailscanner.globexplorer.com/dspam/dspam.cgi?signatureID=4534936b271274356172766&user=gsw@globexplorer.com&retrain=spam&template=history&history_page=1"
!DSPAM:4534936b271274356172766!
-------------------------------------------------------

On Tue, Oct 17, 2006 at 03:39:21PM +0800, Felix Zhang wrote:

> I want to split a table to 2 small tables. The 1st one contains 60%
> records which are randomly selected from the source table.  How to do
> it?

i do my A/B-Group splitting usually by &1 the serial of the table.
assuming, that there are no irregularities in the process of creating
your entries, this should give a 50/50 split, which is reuseable for
future things and there never is a intersection of the two groups.

--
cu