Re: Question on execution plan and suitable index

On 2/15/26 11:04, yudhi s wrote:
> Hi,
> It's postgres version 17. We are having a critical UI query which runs
> for ~7 seconds+. The requirement is to bring down the response time
> within ~1 sec. Now in this plan , If i read this correctly, the below
> section is consuming a significant amount of resources and should be
> addressed. i.e. "Full scan of table "orders" and Nested loop with
> event_audit_log table".

For a start:

1) Supply the complete schema for the tables involved.

2) Also what is the minor version you are using e.g the x in 17.x?

I also recommend reading:

https://wiki.postgresql.org/wiki/Slow_Query_Questions

>
> *Below is the query and its complete plan:- *
> https://gist.github.com/databasetech0073/
> f564ac23ee35d1f0413980fe4d00efa9 <https://gist.github.com/
> databasetech0073/f564ac23ee35d1f0413980fe4d00efa9>
>
> I am a bit new to the indexing strategy in postgres. My question is,
> what suitable index should we create to cater these above?
>
> 1)For table event_audit_log:- Should we create composite Index on column
> (request_id,created_at,event_comment_text) or should we create the
> covering index i.e. just on two column (request_id,created_at) with
> "include" clause for "event_comment_text". How and when the covering
> index indexes should be used here in postgres. Want to understand from
> experts?
> 2)Similarly for table orders:- Should we create a covering index on
> column (entity_id,due_date,order_type) with include clause
> (firm_dspt_case_id). Or just a composite index
> (entity_id,due_date,order_type).
> 3)Whether the column used as range operator (here created_at or
> due_date) should be used as leading column in the composite index or is
> it fine to keep it as non leading?
>
> ->  Nested Loop  (cost=50.06..2791551.71 rows=3148 width=19) (actual
> time=280.735..7065.313 rows=57943 loops=3)
>  Buffers: shared hit=10014901
>  ->  Hash Join  (cost=49.49..1033247.35 rows=36729 width=8) (actual
> time=196.407..3805.755 rows=278131 loops=3)
> Hash Cond: ((ord.entity_id)::numeric = e.entity_id)
> Buffers: shared hit=755352
> ->  Parallel Seq Scan on orders ord  (cost=0.00..1022872.54 rows=3672860
> width=16) (actual time=139.883..3152.627 rows=2944671 loops=3)
>  Filter: ((due_date >= '2024-01-01'::date) AND (due_date <=
> '2024-04-01'::date) AND (order_type = ANY ('{TYPE_A,TYPE_B}'::text[])))
>  Rows Removed by Filter: 6572678
>  Buffers: shared hit=755208
>
>
> Regards
> Yudhi

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com