Re: Getting a random row

Sorry, I guess I wasn't clear.
I have an existing table in my DB, and it doesn't have a column with serial
values (actually it did originally, but due to later deletions of about 2/3
of the rows the column now has "holes"). I realize I could add a new serial
column, but prefer not to change table + the new column would also become
nonconsecutive after further deletions. The nice thing about Oracle's
"rownum" is that it' a pseudo-column", not a real one, and AFAIK is always
valid.

Suggestions?

-- Shaul

2009/10/13 Grzegorz Jaśkiewicz <gryzman(at)gmail(dot)com>

>
>
> On Tue, Oct 13, 2009 at 4:17 PM, Shaul Dar <shauldar(at)gmail(dot)com> wrote:
>
>> Hi,
>>
>> I am running performance simulation against a DB. I want to randomly pull
>> different records from a large table. However the table has no columns that
>> hold sequential integer values (1..MAX), i.e. the columns all have "holes"
>> (due to earlier filtering).
>>
> what do yo umean ? you can restrict range of integer column (or any other
> type) with constraints, for instance CHECK foo( a between 1 and 100);
>
>
>> Also PG does not have a concept of an auto-increment pseudo-column like
>> Oracle's "rownum". Any suggestions?
>>
> not true - it has sequences, and pseudo type serial. Rtfm!.
>
>
>
> --
> GJ
>