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From: Achilleas Mantzios <achill@matrix.gatewaynet.com>
Organization: Dynacom Tankers Mgmt
To: pgsql-sql@postgresql.org
Subject: Fwd: Re: [GENERAL] How to split a table?
Date: Tue, 17 Oct 2006 14:08:44 +0300
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I forgot to mention that you would have to maintain a counter of each inser=
ted=20
row and stop when you reach 60% of N (where N the cardinality of your sourc=
e=20
table).

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Subject: Re: [SQL] [GENERAL] How to split a table?
Date: =D4=F1=DF=F4=E7 17 =CF=EA=F4=FE=E2=F1=E9=EF=F2 2006 12:09
=46rom: Achilleas Mantzios <achill@matrix.gatewaynet.com>
To: pgsql-sql@postgresql.org

=D3=F4=E9=F2 =D4=F1=DF=F4=E7 17 =CF=EA=F4=FE=E2=F1=E9=EF=F2 2006 11:34, =EF=
/=E7 Andreas Kretschmer =DD=E3=F1=E1=F8=E5:
> 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?

In any case, you could write a program in perl and insert into the second
table rows from the first table, using a techique of generarting random
double precision numbers in a predetermined range (lets say 0 to 2^31-1), a=
nd
then converting this number to your "range" like this:
let your number be r.
let your table's cardinality be N.
then let R=3D(N*r/(2^31))+1

select a source row from your table like:

select * from srctable order by pk offset <R>,
and then insert this row to your desttable.

> Andreas

=2D-
Achilleas Mantzios

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=2D-=20
Achilleas Mantzios