Re: Tips for re-using function results within single insert

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От Richard Huxton
Тема Re: Tips for re-using function results within single insert
Дата
Msg-id 200209231245.32139.dev@archonet.com
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Ответ на Tips for re-using function results within single insert  (Chris Gamache <cgg007@yahoo.com>)
Ответы Re: Tips for re-using function results within single insert
Список pgsql-general
On Friday 20 Sep 2002 5:52 pm, Chris Gamache wrote:
> This would be nice to be able to do...
>
> insert into test_table (a,b) select random()::text as "myrandom",
>   encode("myrandom",'base64');

Well, I'd be tempted to write a wrapper function tagged as "iscachable" and
call it with a parameter of the current transaction-id (see docs on trigger
functions) or current time (the one from now() which doesn't change per
transaction). If this gives you grief, try a standard constant.

This means PG will cache results as long as the parameter doesn't change, in
this case for the duration of the transaction.

HTH

- Richard Huxton

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