Re: Statistics Import and Export

On Thu, Feb 27, 2025 at 10:01 PM Corey Huinker <corey(dot)huinker(at)gmail(dot)com>
wrote:

> +--- error: relation is wrong type
>> +SELECT pg_catalog.pg_restore_relation_stats(
>> + 'relation', 0::oid,
>> + 'relpages', 17::integer,
>> + 'reltuples', 400.0::real,
>> + 'relallvisible', 4::integer);
>>
>> Why do you need to specify all the stats (relpages, reltuples, etc)?
>> To exercise this you could just do:
>> select pg_catalog.pg_restore_relation_stats('relation', 0::oid);
>>
>
> In the above case, it's historical inertia in that the pg_set_* call
> required all those parameters, as well as a fear that the code - now or in
> the future - might evaluate "can anything actually change from this call"
> and short circuit out before actually trying to make sense of the reg_class
> oid. But we can assuage that fear with just one of the three stat
> parameters, and I'll adjust accordingly.
>

* reduced relstats parameters specified to the minimum needed to verify the
error and avoid a theoretical future logic short-circuit described above.
* version parameter usage reduced to absolute minimum - verifying that it
is accepted and ignored, though Melanie's patch may introduce a need to
bring it back in a place or two.

84 lines deleted. Not great, not terrible.

I suppose if we really trusted the TAP test databases to have "one of
everything" in terms of tables with all the datatypes, and sufficient rows
to generate interesting stats, plus some indexes of each, then we could get
rid of those two, but I feel very strongly that it would be a minor savings
at a major cost to clarity.