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Fwd: [HACKERS] [PATCH] Pattern based listeners for asynchronousmessaging (LISTEN/NOTIFY) - Mailing list pgsql-hackers

From Markus Sintonen
Subject Fwd: [HACKERS] [PATCH] Pattern based listeners for asynchronousmessaging (LISTEN/NOTIFY)
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Msg-id CAMpj9JaoaZmTLVqCxk5LOaTropBHOC8REpwh1cwuhXzrB=0d1A@mail.gmail.com
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In response to [HACKERS] [PATCH] Pattern based listeners for asynchronous messaging (LISTEN/NOTIFY)  (Markus Sintonen <markus.sintonen@gmail.com>)
Responses Re: [HACKERS] [PATCH] Pattern based listeners for asynchronousmessaging (LISTEN/NOTIFY)  (Marko Tiikkaja <marko@joh.to>)
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I also encountered this when I built it with different configuration. I attached updated patch with the correct number of arguments to 'similar_escape'. I also added preliminary documentation to the patch. 
(Unfortunately unable to currently compile the documentation for testing purpose on Windows probably because of commit https://github.com/postgres/postgres/commit/510074f9f0131a04322d6a3d2a51c87e6db243f9. I followed https://www.postgresql.org/docs/devel/static/install-windows-full.html#idm45412738673840.)

What do you think about the syntax? There was a suggestion to specify type of the pattern (eg ltree extension) but to me this feels like a overkill.
One option here would be eg:
LISTEN PATTERN 'foo%' TYPE 'similar'
LISTEN PATTERN 'foo.*' TYPE 'ltree'
... and so on

BR
-Markus 

2017-08-19 2:36 GMT+03:00 Thomas Munro <thomas.munro@enterprisedb.com>:
On Tue, Aug 1, 2017 at 8:13 AM, Markus Sintonen
<markus.sintonen@gmail.com> wrote:
> This patch adds an ability to use patterns in LISTEN commands. Patch uses
> 'SIMILAR TO' patterns for matching NOTIFY channel names
> (https://www.postgresql.org/docs/9.0/static/functions-matching.html#FUNCTIONS-SIMILARTO-REGEXP).
>
> This patch is related to old discussion in
> https://www.postgresql.org/message-id/52693FC5.7070507@gmail.com. This
> discussion contains the reasoning behind the pattern based matching of the
> channel names.

Nice idea.

The "async" regression test consistently crashes on my FreeBSD box
when built with -O2.  It doesn't crash on another system I tried, and
I think that's just luck, because this:

+               /* convert to regex pattern */
+               datum = DirectFunctionCall1(similar_escape,
CStringGetTextDatum(pattern));

... is calling a function that takes two arguments, but passing only
one.  The second argument is random junk, so similar_escape bombs when
it does this:

        esc_text = PG_GETARG_TEXT_PP(1);

--
Thomas Munro
http://www.enterprisedb.com


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