Re: SQL/JSON: JSON_TABLE

From: Andrew Dunstan <andrew(at)dunslane(dot)net>
To: Andres Freund <andres(at)anarazel(dot)de>
Cc: Stephen Frost <sfrost(at)snowman(dot)net>, Erikjan Rijkers <er(at)xs4all(dot)nl>, Himanshu Upadhyaya <upadhyaya(dot)himanshu(at)gmail(dot)com>, Julien Rouhaud <rjuju123(at)gmail(dot)com>, Nikita Glukhov <n(dot)gluhov(at)postgrespro(dot)ru>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, Dmitry Dolgov <9erthalion6(at)gmail(dot)com>, Oleg Bartunov <obartunov(at)gmail(dot)com>
Subject: Re: SQL/JSON: JSON_TABLE
Date: 2022-04-06 17:56:26
Message-ID: f0070456-5f8a-9e37-bfc7-ed15c880c87b@dunslane.net
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On 4/6/22 12:59, Andres Freund wrote:
> Hi,
>
> On 2022-04-06 11:50:11 -0400, Andrew Dunstan wrote:
>> It does work, but Tom prefers not to have the test at all, so I'll just
>> rip it out.
> If I understand correctly the reason a large table is needed is to test
> parallelism, right? Wouldn't the better fix be to just tweak the parallelism
> settings for that table? See select_parallel.sql:
>
> -- encourage use of parallel plans
> set parallel_setup_cost=0;
> set parallel_tuple_cost=0;
> set min_parallel_table_scan_size=0;
> set max_parallel_workers_per_gather=4;
>
> might be worth also setting
> set parallel_leader_participation = off;
>
> to avoid the leader processing everything before workers have even started up.
>

OK, done that way, thanks. I also kept the table as unlogged and dropped
it at the end.

cheers

andrew

--
Andrew Dunstan
EDB: https://www.enterprisedb.com

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