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Re: WIP: default values for function parameters

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Peter Eisentraut <peter_e(at)gmx(dot)net>
Cc: pgsql-hackers(at)postgresql(dot)org, "Pavel Stehule" <pavel(dot)stehule(at)gmail(dot)com>
Subject: Re: WIP: default values for function parameters
Date: 2008-11-25 01:20:58
Message-ID: 8431.1227576058@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Peter Eisentraut <peter_e(at)gmx(dot)net> writes:
> On Monday 24 November 2008 23:21:15 Pavel Stehule wrote:
>> Default parameters are implemented similar to variadic functions - so
>> no changes on PL part - all changes are on caller part.

> Then I don't understand why you need this special data type instead of using 
> an array of text with nulls for parameters without default.

I'm not even sure you need to store any nulls.  We're going to require
defaults to be provided for the last N parameters consecutively, right?
So that's just what the array contents are.  Or maybe it's not an array
at all but a single text item containing the representation of a List
--- compare the storage of index expressions.  There shouldn't be any
need to read the contents of the value during function resolution;
an appropriate representation will have the number of non-defaultable
parameters stored as a separate integer column.

			regards, tom lane

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