| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk> |
| Cc: | "Daniel Verite" <daniel(at)manitou-mail(dot)org>, "Robert Schreiber" <bobschreiber(at)charter(dot)net>, pgsql-bugs(at)lists(dot)postgresql(dot)org |
| Subject: | Re: PostgreSQL 9.3.5 substring(text from pattern for escape) bug |
| Date: | 2019-05-12 03:50:43 |
| Message-ID: | 27602.1557633043@sss.pgh.pa.us |
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| Lists: | pgsql-bugs |
Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk> writes:
> I looked up the spec on this point. As far as I can see, we're not
> following it, but neither does the spec do what the OP wanted; in fact
> the result should have included the _leading_ Q as well as the trailing
> one.
Huh, interesting. So we should be translating the initial substring
to a non-greedy pattern. I believe Spencer's engine can handle that
by sticking (?:...){1,1}? around it.
Come to think of it, we probably need to be putting (?:...) around
the trailing substring as well. I suspect what we're doing today
produces non-spec results if "|" appears in the trailing part.
regards, tom lane
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