From: Tom Lane <tgl@sss.pgh.pa.us>
To: Jeff Janes <jeff.janes@gmail.com>
cc: Erwin Brandstetter <brsaweda@gmail.com>, pgsql-bugs@lists.postgresql.org
Subject: Re: Variable substitution in jsonb functions fails for jsonpath
 operator like_regex
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Comments: In-reply-to Jeff Janes <jeff.janes@gmail.com>
	message dated "Wed, 18 Oct 2023 20:42:21 -0400"
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Date: Wed, 18 Oct 2023 21:46:29 -0400
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Jeff Janes <jeff.janes@gmail.com> writes:
> On Wed, Oct 18, 2023 at 5:20 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Maybe it wouldn't take more than s/STRING_P/starts_with_initial/
>> here (though I'd then rename starts_with_initial to something
>> more generic).

> I tried it, and it didn't work.  No error, it just doesn't match
> anything--including literal values which do match things in HEAD.

Oh, duh, makeItemLikeRegex() is expecting a plain JsonPathString,
and JsonPathParseItem.value.like_regex is set up for just a
constant pattern.  We could no doubt fix that, but it's a bigger
lift than I was hoping.

> Maybe the problem is that the regex pattern is compiled at the same time
> the jsonpath is compiled?

Doesn't look that way to me: executeLikeRegex is just using
RE_compile_and_execute every time.  (It's "caching" a text datum
representing the pattern string, which might be a good candidate for
the silliest use of caching I've ever seen in PG; it's surely not
buying any useful increment of performance.)

			regards, tom lane