Re: type aliases - Mailing list pgsql-general

From Tom Lane
Subject Re: type aliases
Date
Msg-id 24951.1392485101@sss.pgh.pa.us
Whole thread Raw
In response to Re: type aliases  (David Johnston <polobo@yahoo.com>)
List pgsql-general
David Johnston <polobo@yahoo.com> writes:
> James Harper wrote
>> So suppose I wanted to implement myvarchar in C. In my _in function, how
>> do I know how big my column declaration is? Eg if someone tries to insert
>> 50 characters into my 42 character field, how do I get the declared length
>> and then tell postgres that the data to be inserted is too big?

> There is no current way for a function body to examine the type modifiers of
> its input, domain or otherwise.

Actually the point here is to know the required type modifier of the
*output*.  Type input functions do get passed the target typmod, as a
separate argument.  See varcharin() for an example.

            regards, tom lane


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