Re: dexter on AWS RDS auto tune queries

Thank you @Julian

@Christophe: yes I am using RDS performance insights, however it might
be more helpful if it could give more info about the slowness of the
queries and what improvements could be done to the queries itself.

I am using pgMusted to analyze a slow query and there the suggestion is to
create an index on app2.user_id, however app2.user_id is a primary key.

below is the query and its explain:

select * from (
SELECT
act.*,
app1.user_name AS created_by_username,
app2.user_name AS last_updated_by_username
FROM
account_transactions AS act LEFT OUTER JOIN app_user AS app1 ON
app1.user_id = act.created_by
LEFT OUTER JOIN app_user AS app2 ON app2.user_id = act.last_updated_by
WHERE act.is_deleted = 'false' AND
act.CREATION_DATE BETWEEN TO_DATE('06/06/2021', 'DD-MM-YYYY')
AND TO_DATE('07-06-2021', 'DD-MM-YYYY')
ORDER BY act.ID DESC
) as items order by id desc

Sort (cost=488871.14..489914.69 rows=417420 width=270) (actual
time=2965.815..2979.921 rows=118040 loops=1)
Sort Key: act.id DESC
Sort Method: quicksort Memory: 57607kB
-> Merge Left Join (cost=422961.21..449902.61 rows=417420 width=270)
(actual time=2120.021..2884.484 rows=118040 loops=1)
Merge Cond: (act.last_updated_by = ((app2.user_id)::numeric))
-> Sort (cost=7293.98..7301.62 rows=3054 width=257) (actual
time=464.243..481.292 rows=118040 loops=1)
Sort Key: act.last_updated_by
Sort Method: quicksort Memory: 50899kB
-> Nested Loop Left Join (cost=0.87..7117.21 rows=3054
width=257) (actual time=0.307..316.148 rows=118040 loops=1)
-> Index Scan using creation_date on
account_transactions act (cost=0.44..192.55 rows=3054 width=244) (actual
time=0.295..67.330 rows=118040 loops=1)
" Index Cond: ((creation_date >=
to_date('06/06/2021'::text, 'DD-MM-YYYY'::text)) AND (creation_date <=
to_date('07-06-2021'::text, 'DD-MM-YYYY'::text)))"
Filter: ((is_deleted)::text = 'false'::text)
-> Index Scan using app_user_pk on app_user app1
(cost=0.43..2.27 rows=1 width=21) (actual time=0.002..0.002 rows=1
loops=118040)
Index Cond: (user_id = act.created_by)
-> Sort (cost=415667.22..423248.65 rows=3032573 width=21) (actual
time=1655.748..1876.596 rows=3079326 loops=1)
Sort Key: ((app2.user_id)::numeric)
Sort Method: quicksort Memory: 335248kB
-> Seq Scan on app_user app2 (cost=0.00..89178.73
rows=3032573 width=21) (actual time=0.013..575.630 rows=3032702 loops=1)
Planning Time: 2.222 ms
Execution Time: 3009.387 ms

On Mon, Jun 7, 2021 at 8:00 AM Christophe Pettus <xof(at)thebuild(dot)com> wrote:

>
>
> > On Jun 6, 2021, at 21:51, Ayub Khan <ayub(dot)hp(at)gmail(dot)com> wrote:
> > Other than Dexter, Is there an auto tune or query performance indicator
> for postgres ?
>
> Generally, auto-creating indexes isn't a great idea. I respect the work
> that went into Dexter, but it's much better to find the queries and study
> them, then decide if index creation is the right thing.
>
> RDS has Performance Insights, which is a very useful tool for finding
> where the load on your server is actually coming from.

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