Re: [PERFORM] IMMUTABLE function's flag do not work: 7.3.4, plpgsql

2003-10-10 Thread Andriy Tkachuk 
On Thu, 9 Oct 2003, Gaetano Mendola wrote:

 Andriy Tkachuk wrote:
  On Wed, 8 Oct 2003, Tom Lane wrote:
 
 
 Andriy Tkachuk [EMAIL PROTECTED] writes:
 
 At second. calc_total() is immutable function:
 but it seems that it's not cached in one session:
 
 It's not supposed to be.
 
 
  but it's written id doc:
 
IMMUTABLE indicates that the function always  returns  the  same
result when given the same argument values; that is, it does not
do database lookups or otherwise use  information  not  directly
present in its parameter list. If this option is given, any call
of the function with all-constant arguments can  be  immediately
replaced with the function value.

 The doc say can be not must and will be.

ok, but on what it depends on?

thanks,
 andriy

http://www.imt.com.ua


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Re: [PERFORM] IMMUTABLE function's flag do not work: 7.3.4, plpgsql

2003-10-09 Thread Andriy Tkachuk 
On Wed, 8 Oct 2003, Tom Lane wrote:

 Andriy Tkachuk [EMAIL PROTECTED] writes:
  At second. calc_total() is immutable function:
  but it seems that it's not cached in one session:

 It's not supposed to be.

but it's written id doc:

  IMMUTABLE indicates that the function always  returns  the  same
  result when given the same argument values; that is, it does not
  do database lookups or otherwise use  information  not  directly
  present in its parameter list. If this option is given, any call
  of the function with all-constant arguments can  be  immediately
  replaced with the function value.

I meant that the result of calc_total() is not immediately replaced with the function 
value
as it's written in doc, but it takes as long time as the first function call
in the session (with the same arguments).

Maybe i misunderstand something?

Thank you,
 Andriy Tkachuk.

http://www.imt.com.ua


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Re: [PERFORM] IMMUTABLE function's flag do not work: 7.3.4, plpgsql

2003-10-08 Thread Tom Lane 
Andriy Tkachuk [EMAIL PROTECTED] writes:
 At second. calc_total() is immutable function:
 but it seems that it's not cached in one session:

It's not supposed to be.

The reason the runtime is small in your example is that the planner
executes the function call while preparing the plan, and this isn't
counted in EXPLAIN's runtime measurement.  There's no claim anywhere
that the results of such an evaluation would be saved for other plans.

regards, tom lane

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