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Trigger vs Rule
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* Trigger vs Rule
@ 2006-04-02 08:31  Ключников А.С. <alexs@analytic.mv.ru>
  0 siblings, 1 reply; 4+ messages in thread

From: Ключников А.С. @ 2006-04-02 08:31 UTC (permalink / raw)
  To: pgsql-performance

Hi all.

There are two tables:

create table device_types (
id int,
name varchar
);
about 1000 rows

create table devices (
id int,
type int REFERENCES device_types(id),
name varchar,
data float
);
about 200000 rows

And about 1000 functions:
create function device_type1(int) returns ..
create function device_type2(int) returns ..
...
create function device_type1000(int) returns ..


What is faster?

One trigger with 1000 ELSE IF
if old.type=1 then 
    select device_type1(old.id);
else if old.type=2 then
	select device_type2(old.id);
...
else if old.type=1000 then
	select device_type1000(old.id);
end if;

Or 1000 rules
create rule device_type1 AS ON update to devices 
	where old.type=1  
    DO select device_type1(old.id);
create rule device_type2 AS ON update to devices 
    where old.type=2
    DO select device_type2(old.id);
...
create rule device_type1000 AS ON update to devices 
    where old.type=1000
    DO select device_type1000(old.id);

thx.

-- 
С уважением,
Ключников А.С.



^ permalink  raw  reply  [nested|flat] 4+ messages in thread

* Re: Trigger vs Rule
@ 2006-04-02 21:08  Niklas Johansson <spot@tele2.se>
  parent: Ключников А.С. <alexs@analytic.mv.ru>
  0 siblings, 1 reply; 4+ messages in thread

From: Niklas Johansson @ 2006-04-02 21:08 UTC (permalink / raw)
  To: Ключников А.С. <alexs@analytic.mv.ru>; +Cc: pgsql-performance


On 2 apr 2006, at 10.31, Ключников А.С. wrote:
> What is faster?
> One trigger with 1000 ELSE IF
> Or 1000 rules

Faster to write and easier to maintain would be to write a trigger  
function in pl/pgsql which executes the right function dynamically:

CREATE OR REPLACE FUNCTION exec_device_type() RETURNS trigger AS $$
	EXECUTE "SELECT device_type" || OLD.type || "(OLD.id)";
$$ LANGUAGE plpgsql;

Best would probably be to refactor your device_typeN() functions into  
one, that would take N as an argument.


Sincerely,

Niklas Johansson







^ permalink  raw  reply  [nested|flat] 4+ messages in thread

* Re: Trigger vs Rule
@ 2006-04-03 09:04  Niklas Johansson <spot@tele2.se>
  parent: Niklas Johansson <spot@tele2.se>
  0 siblings, 1 reply; 4+ messages in thread

From: Niklas Johansson @ 2006-04-03 09:04 UTC (permalink / raw)
  To: "Ключников А.С." <alexs@analytic.mv.ru>; +Cc: pgsql-performance


On 2 apr 2006, at 23.08, Niklas Johansson wrote:

> CREATE OR REPLACE FUNCTION exec_device_type() RETURNS trigger AS $$
> 	EXECUTE "SELECT device_type" || OLD.type || "(OLD.id)";
> $$ LANGUAGE plpgsql;


Sorry, I was bitten by the bedbug there: a plpgsql function needs a  
little more than that to be functional :)

CREATE OR REPLACE FUNCTION exec_device_type() RETURNS trigger AS $$
BEGIN
	EXECUTE 'SELECT device_type' || OLD.type || '(OLD.id)';
	RETURN NEW/OLD/NULL; -- Depending on your application.
END;
$$ LANGUAGE plpgsql;

But really, you should consider reworking your schema structure.  
Having a thousand functions doing almost the same thing is neither  
efficient, nor maintainable.



Sincerely,

Niklas Johansson







^ permalink  raw  reply  [nested|flat] 4+ messages in thread

* Re: Trigger vs Rule
@ 2006-04-03 09:17  Ключников А.С. <alexs@analytic.mv.ru>
  parent: Niklas Johansson <spot@tele2.se>
  0 siblings, 0 replies; 4+ messages in thread

From: Ключников А.С. @ 2006-04-03 09:17 UTC (permalink / raw)
  To: pgsql-performance

* Niklas Johansson <spot@tele2.se> [2006-04-03 11:04:25 +0200]:

> 
> On 2 apr 2006, at 23.08, Niklas Johansson wrote:
> 
> >CREATE OR REPLACE FUNCTION exec_device_type() RETURNS trigger AS $$
> >	EXECUTE "SELECT device_type" || OLD.type || "(OLD.id)";
> >$$ LANGUAGE plpgsql;
> 
> 
> Sorry, I was bitten by the bedbug there: a plpgsql function needs a  
> little more than that to be functional :)
> 
> CREATE OR REPLACE FUNCTION exec_device_type() RETURNS trigger AS $$
> BEGIN
> 	EXECUTE 'SELECT device_type' || OLD.type || '(OLD.id)';
> 	RETURN NEW/OLD/NULL; -- Depending on your application.
> END;
> $$ LANGUAGE plpgsql;
> 
> But really, you should consider reworking your schema structure.  
> Having a thousand functions doing almost the same thing is neither  
> efficient, nor maintainable.
Things are very diferent. 
For many types functions not needed, jast update.

I.e. This is a way One trigger with ~1000 else if.
Here was a diametral opinion.  
> 
> 
> 
> Sincerely,
> 
> Niklas Johansson
> 
> 
> 
> 

-- 
С уважением,
Ключников А.С.
Ведущий инженер ПРП "Аналитприбор"
432030 г.Ульяновск, а/я 3117
тел./факс +7 (8422) 43-44-78
mailto: alexs@analytic.mv.ru



^ permalink  raw  reply  [nested|flat] 4+ messages in thread

end of thread, other threads:[~2006-04-03 09:17 UTC | newest]

Thread overview: 4+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2006-04-02 08:31 Trigger vs Rule Ключников А.С. <alexs@analytic.mv.ru>
2006-04-02 21:08 ` Niklas Johansson <spot@tele2.se>
2006-04-03 09:04   ` Niklas Johansson <spot@tele2.se>
2006-04-03 09:17     ` Ключников А.С. <alexs@analytic.mv.ru>

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