Re: preserving forensic information when we freeze

On 2013-12-20 13:22:07 +0100, Andres Freund wrote:
> On 2013-12-20 07:12:01 -0500, Robert Haas wrote:
> > I think the root of the problem is that nobody's very eager to add
> > more hidden system catalog columns because each one bloats
> > pg_attribute significantly.
>
> I think that part is actually solveable - there's no real need for them
> to be real columns, present in pg_attribute, things could easily enough be
> setup during parse analysis.

I've spent some time yesterday hacking up a prototype for this. The
amount of effort seems reasonable, although the attached patch certainly
doesn't do all the neccessary things. The regression tests pass.

In the prototype only oid keeps it's pg_attribute entry, everything else
uses the static entries via
SystemAttributeDefinition()/SystemAttributeByName(). We might want to
remove oids as well, but it seems reasonable to continue allowing
defining column permissions on it. And it's likely the attribute that's
most likely ingrained deeply in user applications.

> The bigger problem I see is that adding
> more useful columns will cause name clashes, which will probably
> prohibit improvements in that direction.

I wonder if we could solve that by naming new columns like
"system:attribute" or similar. Not pretty, but maybe better than the
alternatives.

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
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