Re: [EXTERNAL] RDS IO Read time - Mailing list pgsql-general

From Eden Aharoni
Subject Re: [EXTERNAL] RDS IO Read time
Date
Msg-id PA6PR03MB10241A499332A52D212A752E4BBAD2@PA6PR03MB10241.eurprd03.prod.outlook.com
Whole thread Raw
In response to Re: [EXTERNAL] RDS IO Read time  (Christophe Pettus <xof@thebuild.com>)
List pgsql-general

Aggregate  (cost=8581.22..8581.23 rows=1 width=4) (actual time=1209.498..1210.530 rows=1 loops=1)

  Buffers: shared hit=3108 read=4314 dirtied=1

  I/O Timings: shared read=1169.977

  ->  Gather  (cost=8580.80..8581.21 rows=4 width=8) (actual time=1209.371..1210.526 rows=5 loops=1)

          Workers Planned: 4

          Workers Launched: 4

        Buffers: shared hit=3108 read=4314 dirtied=1

        I/O Timings: shared read=1169.977

        ->  Aggregate  (cost=7580.80..7580.81 rows=1 width=8) (actual time=1206.518..1206.520 rows=1 loops=5)

              Buffers: shared hit=3105 read=4314 dirtied=1

              I/O Timings: shared read=1169.977

              ->  Hash Join  (cost=2620.70..7578.45 rows=937 width=0) (actual time=148.965..1206.330 rows=1897 loops=5)

                    Buffers: shared hit=3105 read=4314 dirtied=1

                    I/O Timings: shared read=1169.977

                    ->  Index Only Scan using IX_Collaborators_TenantId_IsDeleted_RunningIndex on Collaborators c  (cost=0.55..4619.26 rows=11407 width=80) (actual time=2.815..1058.793 rows=7474 loops=5)

                            Index Cond: ((c."TenantId" = '0f8026c775a5499fdd3ccd193a15f94c3b4ae58a'::text) AND (c."IsDeleted" = false))

                            Heap Fetches: 3711

                          Buffers: shared hit=2332 read=3563

                          I/O Timings: shared read=1028.548

                    ->  Hash  (cost=2479.01..2479.01 rows=11292 width=79) (actual time=144.988..144.989 rows=1983 loops=5)

                          Buffers: shared hit=637 read=751 dirtied=1

                          I/O Timings: shared read=141.429

                          ->  Index Only Scan using IX_IntegrationCollaboration_TenantId_IsIntegrationDeleted_IsDe~ on IntegrationCollaboration i  (cost=0.55..2479.01 rows=11292 width=79) (actual time=1.804..144.122 rows=1983 loops=5)

                                  Index Cond: (i."TenantId" = '0f8026c775a5499fdd3ccd193a15f94c3b4ae58a'::text)

                                  Heap Fetches: 112

                                Buffers: shared hit=637 read=751 dirtied=1

                                I/O Timings: shared read=141.429

Planning:

  Buffers: shared hit=440

Execution time: 1210.592 ms

 

So we can see here that the query read 4314 blocks in 1.2 sec.. (ive done 4314 * 8kb / 1.2sec which is about 28 MB/s)…

 

Hope you’ll have any clue 😊

From: Christophe Pettus <xof@thebuild.com>
Date: Monday, 31 March 2025 at 21:44
To: Eden Aharoni <edena@legitsecurity.com>
Cc: pgsql-general@lists.postgresql.org <pgsql-general@lists.postgresql.org>
Subject: Re: [EXTERNAL] RDS IO Read time



> On Mar 31, 2025, at 11:30, Eden Aharoni <edena@legitsecurity.com> wrote:
>
> Can you please tell me what other data might help?

You can show your work on how you got the megabytes/second number.  (Be aware that on a general open-source mailing list, there's only so much debugging that we can do of a specific problem that is not a PostgreSQL bug.)

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