Bruno Wolff III <[EMAIL PROTECTED]> writes:
> Enver ALTIN <[EMAIL PROTECTED]> wrote:
>> I wish I could do something like:
>> select tiptext from tips order by random limit 1
>> in PostgreSQL.
> You can but it won't be very efficient (for large tables) as it will generate
> a random ordering for the whole table, probably do a sort and then return the
> first record. The only thing different you need to do is add () after random:
> select tiptext from tips order by random() limit 1
If you do need to do this for a large table, I seem to recall that
we've previously worked out reasonable ways to select a random entry
efficiently using an index. Dig around in the mail list archives for
details.
regards, tom lane
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TIP 9: the planner will ignore your desire to choose an index scan if your
joining column's datatypes do not match
