I don't know the PG features you are using, I can only guess that the fields text and keywordhash are both the same JSON string.

Using a regex here is not a wise decision, even with proper delimiters (which are dangerously lacking).

If destructing¹ the hash is fine I'd try delete @kws{@kwlist} (see delete and hash slice) and calculate the difference of scalar keys %kws before and after.

But - as you already mentioned- I suppose PG has already a built-in hash slice feature you could use for faster execution.

Cheers Rolf
(addicted to the Perl Programming Language :)
see Wikisyntax for the Monastery

update

FWIW your use of defined is also error prone, exists it's the way to go.

Footnotes

¹) and if destructing is not ok consider delete local @kws{@kwlist} , DISCLAIMER I've never used it, wasn't even actively aware of it.

In reply to Re: Faster of two options for finding keywords in a database by LanX
in thread Faster of two options for finding keywords in a database by cormanaz

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