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Re: help regarding function valatality categories

From: Chetan Suttraway <chetan(dot)suttraway(at)enterprisedb(dot)com>
To: siva kiran balijepalli <b(dot)sivakiran(at)gmail(dot)com>
Cc: pgsql-novice(at)postgresql(dot)org
Subject: Re: help regarding function valatality categories
Date: 2011-03-15 06:05:57
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-novice
On Mon, Mar 14, 2011 at 2:26 PM, siva kiran balijepalli <
b(dot)sivakiran(at)gmail(dot)com> wrote:

> Hi all,
> can anybody explain with simple example regarding the function valatality
> categories such as VOLATILE/STABLE/IMMUTABLE
> I have gone throught the documnetation but didn't had better understanding?
> please reply
> regards
> siva kiran.B

Basically its like asking the behavior in case of a global variable being
accessed by few functions at same time.
Should each function be having separate copy or everyone sees the updated
copy in real time?

Based on this decision, we can specify the function volatility categories.

Also note that this classification of functions is similar to what we have
in other programming languages.
For ex, C programming.

These are categories of functions for better understanding of work that is
going to happen inside them.
And  this information will be used by the query optimizer in some way while
generating query plans.

Maybe google will help you further in this query :)


Chetan Sutrave
Senior Software Engineer
EnterpriseDB Corporation
The Enterprise PostgreSQL Company
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