Re: Performance of JSON_TABLE vs jsonb_to_recordset

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Alexander Lakhin <exclusion(at)gmail(dot)com>
Cc: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Performance of JSON_TABLE vs jsonb_to_recordset
Date: 2024-04-20 14:47:37
Message-ID: 2448626.1713624457@sss.pgh.pa.us
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Alexander Lakhin <exclusion(at)gmail(dot)com> writes:
> When playing with JSON_TABLE, I tried to replace tenk1 in regression tests
> with a view based on JSON_TABLE, with the same content, and discovered
> that for one sub-optimal query it's execution duration increased many-fold.
> With the preparation script attached, I see the following durations
> (for a build compiled by clang 18.1.3 with -O3):
> explain (verbose, analyze)
> select
>   (select max((select i.unique2 from tenk1 i where i.unique1 = o.unique1)))
> from tenk1 o;
> -- original tenk1
>  Execution Time: 4769.481 ms

Hm, I get about 13 ms for that example. Do you have some really
expensive debugging infrastructure enabled, perhaps?

regards, tom lane

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