Re: query_id: jumble names of temp tables for better pg_stat_statement UX

On Wed, Mar 19, 2025 at 01:02:54PM +0100, Christoph Berg wrote:
> You are of course right, that one-line comment was just snakeoil :D.
> Now there are proper ones, thanks.

I have been thinking about this patch for a couple of days. What
makes me unhappy in this proposal is that RangeTblEntry is a large and
complicated Node, and we only want to force a custom computation for
the "relid" portion of the node, while being able to also take some
decisions for what the parent node has. Leaving the existing
per-field query_jumble_ignore with the custom function is prone to
errors, as well, because we need to maintain some level of consistency
between parsenodes.h and src/backend/nodes/.

Hence here is a counter-proposal, that can bring the best of both
worlds: let's add support for custom_query_jumble at field level.
I've spent some time on that, and some concatenation in a macro used
by gen_node_support.pl to force a policy for the custom function name
and its arguments is proving to be rather straight-forward. This
approach addresses the problem of this thread, while also tackling my
concerns about complex node structures.

The custom functions are named _jumble${node}_${field}, with the field
and the parent node given as arguments. I agree that giving the field
is kind of pointless if you have the parent node, but I think that
this is better so as this forces developers to think about how to use
the field value with the node.

Please see the attached. What do you think?
--
Michael