Re: ALTER TABLE ADD COLUMN fast default

On Thu, Mar 29, 2018 at 10:19 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> 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?
>


That's what we started with and Andres suggested we change it. One
virtue of the array is that is displays nicely when examining
pg_attribute. But changing it back would be easy enough.

cheers

andrew

-- 
Andrew Dunstan                https://www.2ndQuadrant.com
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