I forgot to mention that you would have to maintain a counter of each inserted row and stop when you reach 60% of N (where N the cardinality of your source table).
---------- Προωθημένο Μήνυμα ---------- Subject: Re: [SQL] [GENERAL] How to split a table? Date: Τρίτη 17 Οκτώβριος 2006 12:09 From: Achilleas Mantzios <[EMAIL PROTECTED]> To: pgsql-sql@postgresql.org Στις Τρίτη 17 Οκτώβριος 2006 11:34, ο/η Andreas Kretschmer έγραψε: > Felix Zhang <[EMAIL PROTECTED]> 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), and then converting this number to your "range" like this: let your number be r. let your table's cardinality be N. then let R=(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 -- Achilleas Mantzios ------------------------------------------------------- -- Achilleas Mantzios ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
