Re: Variable length varlena headers redux - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Variable length varlena headers redux
Date
Msg-id 24763.1171033878@sss.pgh.pa.us
Whole thread Raw
In response to Re: Variable length varlena headers redux  (Greg Stark <gsstark@mit.edu>)
Responses Re: Variable length varlena headers redux  (Gregory Stark <stark@enterprisedb.com>)
Re: Variable length varlena headers redux  (Greg Stark <gsstark@mit.edu>)
List pgsql-hackers
Greg Stark <gsstark@mit.edu> writes:
> Bruce Momjian <bruce@momjian.us> writes:
>> I know it is kind of odd to have a data type that is only used on disk,
>> and not in memory, but I see this as a baby varlena type, used only to
>> store and get varlena values using less disk space.

> I was leaning toward generating the short varlena headers primarily in
> heap_form*tuple and just having the datatype specific code generate 4-byte
> headers much as you describe.

I thought we had a solution for all this, namely to make the short-form
headers be essentially a TOAST-compressed representation.  The format
with 4-byte headers is still legal but just not compressed.  Anyone who
fails to detoast an input argument is already broken, so there's no code
compatibility hit taken.
        regards, tom lane


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