public inbox for [email protected]
help / color / mirror / Atom feedFrom: Masahiro Ikeda <[email protected]>
To: torikoshia <[email protected]>
Cc: Bharath Rupireddy <[email protected]>
Cc: Fujii Masao <[email protected]>
Cc: Dilip Kumar <[email protected]>
Cc: Pgsql Hackers <[email protected]>
Subject: Re: RFC: Logging plan of the running query
Date: Tue, 13 Jul 2021 23:11:37 +0900
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
<CAFiTN-vE4Q6=bJ-n9hNz8qwkaw2NK1scNC5LrSFkREex+XymLg@mail.gmail.com>
<CALj2ACXDiOhAdXks_w2b5NGg=7_K27Lx1Gau_iQnxGBCNkSMnQ@mail.gmail.com>
<CALj2ACXpvVeLstnNG1Oris0VpxbSdLNdh_r-v6YxTEY5vcDHAA@mail.gmail.com>
<CAFiTN-tbi83fB0j0S7-kj9TraUkim03M3S+oXdYe6sMZ7nxVYA@mail.gmail.com>
<CALj2ACVH-fhO5htnM2UbV7mvP3+0+zYHBamCTC8KWTtSb5+8=g@mail.gmail.com>
<CAFiTN-vQcDtyc5aRF1RNo-VgRzMcZ4E1qKTybvHpzUV1FEjqBA@mail.gmail.com>
<CALj2ACWiVHpOqEztxHRtUR1oiDzPGUnguqv2EfEmQSv7jH93aw@mail.gmail.com>
<CAFiTN-vOTFRK1xoAWRAGJ+54mSpDxmenAFexbySRhgy7hNH5Fg@mail.gmail.com>
<CAFiTN-u6yqaxQyfX0jUMqDZ22fePfuQuQmzuozTxC34ca+ZByg@mail.gmail.com>
<[email protected]>
<[email protected]>
<CALj2ACUpznbsLbOg9mauSQZfU2eDxnNLYXcBHaAp1yWxMKLK9g@mail.gmail.com>
<[email protected]>
<CALj2ACVeOvBcN2-MZh-P3FKxsxOv-DD=fUgAMQEY8vPEhoJUQw@mail.gmail.com>
<[email protected]>
<[email protected]>
<CALj2ACXS8oSHbO_gf==jRLGGDoMR-AoeKhoSfd1uh8kw-keY7g@mail.gmail.com>
<[email protected]>
On Tue, Jun 22, 2021 at 8:00 AM torikoshia <[email protected]>
wrote:
> Updated the patch.
Hi, torikoshi-san
Thanks for your great work! I'd like to use this feature in v15.
I confirmed that it works with queries I tried and make check-world has
no error.
When I tried this feature, I realized two things. So, I share them.
(1) About output contents
> The format of the query plan is the same as when <literal>FORMAT
> TEXT</literal>
> and <literal>VEBOSE</literal> are used in the
> <command>EXPLAIN</command> command.
> For example:
I think the above needs to add COSTS and SETTINGS options too, and it's
better to use an
example which the SETTINGS option works like the following.
```
2021-07-13 21:59:56 JST 69757 [client backend] LOG: plan of the query
running on backend with PID 69757 is:
Query Text: PREPARE query2 AS SELECT COUNT(*) FROM
pgbench_accounts t1, pgbench_accounts t2;
Aggregate (cost=3750027242.84..3750027242.86 rows=1 width=8)
Output: count(*)
-> Nested Loop (cost=0.84..3125027242.84 rows=250000000000
width=0)
-> Index Only Scan using pgbench_accounts_pkey on
public.pgbench_accounts t1 (cost=0.42..12996.42 rows=500000 width=0)
Output: t1.aid
-> Materialize (cost=0.42..15496.42 rows=500000
width=0)
-> Index Only Scan using pgbench_accounts_pkey on
public.pgbench_accounts t2 (cost=0.42..12996.42 rows=500000 width=0)
Settings: effective_cache_size = '8GB', work_mem = '16MB'
```
(2) About EXPLAIN "BUFFER" option
When I checked EXPLAIN option, I found there is another option "BUFFER"
which can be
used without the "ANALYZE" option.
I'm not sure it's useful because your target use-case is analyzing a
long-running query,
not its planning phase. If so, the planning buffer usage is not so much
useful. But, since
the overhead to output buffer usages is not high and it's used for
debugging use cases,
I wonder it's not a bad idea to output buffer usages too. Thought?
Regards,
--
Masahiro Ikeda
NTT DATA CORPORATION
view thread (116+ messages) latest in thread
reply
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: [email protected]
Cc: [email protected], [email protected], [email protected], [email protected], [email protected]
Subject: Re: RFC: Logging plan of the running query
In-Reply-To: <[email protected]>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox