Обсуждение: call by reference vs call by value
How are variables in pg/psql functions passed? I'm sure this is documented somewhere. I looked but no joy. A link would be great! TIA
Mike
How are variables in pg/psql functions passed? I'm sure this is documented somewhere. I looked but no joy. A link would be great! TIA
I doubt its documented anywhere since the concept of "by reference" is not part of the language. The concept is also not part of SQL.
If you want a better explanation you should provide some code for us to comment upon.
David J.
I am trying to translate some Oracle PL/SQL code which has the following signature:
PROCEDURE dGetQuestionSetKeyOrder
(pweb_site_name_i IN tx_web_site.web_site_name%TYPE,
p_sid_i IN varchar2,
pqs_table_i IN OUT NOCOPY XPORTAL_QUESTION_SET_TABLE
)
"NOCOPY" tells oracle that pqs_table_i is call by reference. I was wondering if pgplsql has a similar mechanism. Apparently not. Thanks!
On Tue, Dec 8, 2015 at 11:15 AM, David G. Johnston <david.g.johnston@gmail.com> wrote:
How are variables in pg/psql functions passed? I'm sure this is documented somewhere. I looked but no joy. A link would be great! TIAI doubt its documented anywhere since the concept of "by reference" is not part of the language. The concept is also not part of SQL.If you want a better explanation you should provide some code for us to comment upon.David J.
Hi
2015-12-08 20:07 GMT+01:00 Michael Moore <michaeljmoore@gmail.com>:
How are variables in pg/psql functions passed? I'm sure this is documented somewhere. I looked but no joy. A link would be great! TIA
It is simply - small values are passed by value (to 8bytes), bigger are passed as reference - but all is internal and cannot be controlled from user space.
Search keywords "varlena", "datum", "toast"
Regards
Pavel
Mike
2015-12-08 21:25 GMT+01:00 Michael Moore <michaeljmoore@gmail.com>:
I am trying to translate some Oracle PL/SQL code which has the following signature:PROCEDURE dGetQuestionSetKeyOrder(pweb_site_name_i IN tx_web_site.web_site_name%TYPE,p_sid_i IN varchar2,pqs_table_i IN OUT NOCOPY XPORTAL_QUESTION_SET_TABLE)"NOCOPY" tells oracle that pqs_table_i is call by reference. I was wondering if pgplsql has a similar mechanism. Apparently not. Thanks!
It is totally different - NOCOPY hasn't any sense in Postgres
Pavel
On Tue, Dec 8, 2015 at 11:15 AM, David G. Johnston <david.g.johnston@gmail.com> wrote:How are variables in pg/psql functions passed? I'm sure this is documented somewhere. I looked but no joy. A link would be great! TIAI doubt its documented anywhere since the concept of "by reference" is not part of the language. The concept is also not part of SQL.If you want a better explanation you should provide some code for us to comment upon.David J.
Thanks guys.
On Tue, Dec 8, 2015 at 12:31 PM, Pavel Stehule <pavel.stehule@gmail.com> wrote:
2015-12-08 21:25 GMT+01:00 Michael Moore <michaeljmoore@gmail.com>:I am trying to translate some Oracle PL/SQL code which has the following signature:PROCEDURE dGetQuestionSetKeyOrder(pweb_site_name_i IN tx_web_site.web_site_name%TYPE,p_sid_i IN varchar2,pqs_table_i IN OUT NOCOPY XPORTAL_QUESTION_SET_TABLE)"NOCOPY" tells oracle that pqs_table_i is call by reference. I was wondering if pgplsql has a similar mechanism. Apparently not. Thanks!It is totally different - NOCOPY hasn't any sense in PostgresPavel
On Tue, Dec 8, 2015 at 11:15 AM, David G. Johnston <david.g.johnston@gmail.com> wrote:How are variables in pg/psql functions passed? I'm sure this is documented somewhere. I looked but no joy. A link would be great! TIAI doubt its documented anywhere since the concept of "by reference" is not part of the language. The concept is also not part of SQL.If you want a better explanation you should provide some code for us to comment upon.David J.