On Thu, May 21, 2020 at 08:49:53AM +0200, Julien Rouhaud wrote:
> On Tue, May 19, 2020 at 4:29 AM Andy Fan <zhihui.fan1213@gmail.com> wrote:
>> Thanks for the excellent extension. I want to add 5 more fields to satisfy the
>> following requirements.
>>
>> int subplan; /* No. of subplan in this query */
>> int subquery; /* No. of subquery */
>> int joincnt; /* How many relations are joined */
>> bool hasagg; /* if we have agg function in this query */
>> bool hasgroup; /* has group clause */
>
> Most of those fields can be computed using the raw sql satements. Why
> not adding functions like query_has_agg(querytext) to get the
> information from pgss stored query text instead?
Yeah I personally find concepts related only to the query string
itself not something that needs to be tied to pg_stat_statements.
...
Indeed cte will bring additional concerns about the fields semantics. That's another good reason to go with external functions so you can add extra parameters for that if needed.
There are something more we can't get from query string easily. like:
1. view involved. 2. subquery are pulled up so there is not subquery
indeed. 3. sublink are pull-up or become as an InitPlan rather than subPlan.
4. joins are removed by remove_useless_joins.
--