Re: Planning counters in pg_stat_statements (using pgss_store)

On Fri, Mar 27, 2020 at 12:02 PM Fujii Masao
<masao(dot)fujii(at)oss(dot)nttdata(dot)com> wrote:
>
> On 2020/03/27 19:00, Julien Rouhaud wrote:
> > On Thu, Mar 26, 2020 at 02:22:47PM +0100, Julien Rouhaud wrote:
> >> On Thu, Mar 26, 2020 at 08:08:35PM +0900, Fujii Masao wrote:
> >>>
> >>> Here are other comments.
> >>>
> >>> - if (jstate)
> >>> + if (kind == PGSS_JUMBLE)
> >>>
> >>> Why is PGSS_JUMBLE necessary? ISTM that we can still use jstate here, instead.
> >>>
> >>> If it's ok to remove PGSS_JUMBLE, we can define PGSS_NUM_KIND(=2) instead
> >>> and replace 2 in, e.g., total_time[2] with PGSS_NUM_KIND. Thought?
> >>
> >> Yes, we could be using jstate here. I originally used that to avoid passing
> >> PGSS_EXEC (or the other one) as a way to say "ignore this information as
> >> there's the jstate which says it's yet another meaning". If that's not an
> >> issue, I can change that as PGSS_NUM_KIND will clearly improve the explicit "2"
> >> all over the place.
> >
> > Done, passing PGSS_PLAN when jumble is intended, with a comment saying that the
> > pgss_kind is ignored in that case.
> >
> >>> + <entry><structfield>total_time</structfield></entry>
> >>> + <entry><type>double precision</type></entry>
> >>> + <entry></entry>
> >>> + <entry>
> >>> + Total time spend planning and executing the statement, in milliseconds
> >>> + </entry>
> >>> + </row>
> >>>
> >>> pg_stat_statements view has this column but the function not.
> >>> We should make both have the column or not at all, for consistency?
> >>> I'm not sure if it's good thing to expose the sum of total_plan_time
> >>> and total_exec_time as total_time. If some users want that, they can
> >>> easily calculate it from total_plan_time and total_exec_time by using
> >>> their own logic.
> >>
> >> I think we originally added it as a way to avoid too much compatibility break,
> >> and also because it seems like a field most users will be interested in anyway.
> >> Now that I'm thinking about it again, I indeed think it was a mistake to have
> >> that in view part only. Not mainly for consistency, but for users who would be
> >> interested in the total_time field while not wanting to pay the overhead of
> >> retrieving the query text if they don't need it. So I'll change that!
> >
> > Done
> >
> >>> + nested_level++;
> >>> + PG_TRY();
> >>>
> >>> In old thread [1], Tom Lane commented the usage of nested_level
> >>> in the planner hook. There seems no reply to that so far. What's
> >>> your opinion about that comment?
> >>>
> >>> [1] https://www.postgresql.org/message-id/28980.1515803777@sss.pgh.pa.us
> >>
> >> Oh thanks, I didn't noticed this part of the discussion. I agree with Tom's
> >> concern, and I think that having a specific nesting level variable for the
> >> planner is the best workaround, so I'll implement that.
> >
> > Done.
> >
> > I also exported BufferUsageAccumDiff as mentioned previously, as it seems
> > clearner and will avoid future useless code churn, and run pgindent.
> >
> > v10 attached.
>
> Thanks for updating the patches!
>
> Regarding 0001 patch, I have one nitpicking comment;
>
> - result = standard_planner(parse, cursorOptions, boundParams);
> + result = standard_planner(parse, query_text, cursorOptions, boundParams);
>
> -standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
> +standard_planner(Query *parse, const char *querytext, int cursorOptions,
> + ParamListInfo boundParams)
>
> -pg_plan_query(Query *querytree, int cursorOptions, ParamListInfo boundParams)
> +pg_plan_query(Query *querytree, const char *query_text, int cursorOptions,
> + ParamListInfo boundParams)
>
> The patch uses "query_text" and "querytext" as the name of newly-added
> argument. They should be unified? IMO "query_string" looks better name
> because it's used in other functions like pg_analyze_and_rewrite(),
> pg_parse_query() for the sake of consistency. Thought?

Indeed, and +1 for query_text.