Re: Speeding up query pulling comments from pg_catalog
On Sat, Jul 20, 2019 at 7:46 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
But if you do so manually you'll end up with something like
SELECT c.relname AS table, a.attname AS column, d.description AS comment
FROM
pg_catalog.pg_attribute a JOIN pg_catalog.pg_class c ON a.attrelid = c.oid
LEFT JOIN pg_catalog.pg_description d ON d.classoid = c.tableoid and d.objoid = c.oid and d.objsubid = a.attnum
WHERE d.description IS NOT NULL;
For me, that formulation is quite a bit faster than the original ---
A lot faster for me too (~30-40 ms). Thanks!
and then to add insult to injury, has to search pg_description a second
time for each hit.
Not sure if I'm understanding this correctly, but are you saying that because col_description() is specified in two places in the query, that it actually will get called twice? I was under the impression that a function (at least a non-volatile one) specified multiple times, but with the same arguments, would only get called once. Is that just wishful thinking?
Cheers,
Ken
AGENCY Software
A Free Software data system
By and for non-profits
(253) 245-3801
learn more about AGENCY or
follow the discussion.
В списке pgsql-performance по дате отправления: