Re: ALTER TABLE ADD COLUMN fast default

Andrew Dunstan <andrew.dunstan@2ndquadrant.com> writes:
> On Wed, Mar 28, 2018 at 5:30 PM, Andres Freund <andres@anarazel.de> wrote:
>> +       /*
>> +        * Missing value for added columns. This is a one element array which lets
>> +        * us store a value of the attribute type here.
>> +        */
>> +       anyarray        attmissingval BKI_DEFAULT(_null_);
>> #endif
>> } FormData_pg_attribute;
>>
>> Still think this is a bad location, and it'll reduce cache hit ratio for
>> catalog lookups.

> As I think I mentioned before, this was discussed previously and as I
> understood it this was the consensus location for it.

I don't have a problem with putting that in pg_attribute (and I certainly
agree with not putting it in pg_attrdef).  But "anyarray" seems like a
damn strange, and bulky, choice.  Why not just make it a bytea holding the
bits for the value, nothing more?

            regards, tom lane