Re: [HACKERS] Re: [GENERAL] Re: [PHP3] Re: PostgreSQL vs Mysql comparison - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: [HACKERS] Re: [GENERAL] Re: [PHP3] Re: PostgreSQL vs Mysql comparison
Date
Msg-id 199910090134.VAA22009@candle.pha.pa.us
Whole thread Raw
In response to Re: [HACKERS] Re: [GENERAL] Re: [PHP3] Re: PostgreSQL vs Mysql comparison  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
> Bruce Momjian <maillist@candle.pha.pa.us> writes:
> >> Ah, so the problem was that the perl interface didn't append a newline?
> >> Good catch.  I don't like this fix, however, since I fear it will
> >> alter behavior for the case where there is an embedded newline in the
> >> query buffer.
> 
> > I will commit this so it will always be tested by the perl test code.
> 
> But how often do we run that?

Well, at least it is there now, and I will do --with-perl here, so it
will be run.

> > No, seems lex only goes the end-of-line unless you specifically say \n.
> 
> OK, I see in the flex manual that "." matches everything except newline,
> so I guess it will work.  At least with flex.  But ".*" patterns with
> no clearly defined terminator always make me itch --- it doesn't take
> much change to get the wrong result.

True, but it fixes the problem.

> 
> >> A better solution IMHO is to leave scan.l as it was and instead
> >> always append a \n to the presented query string before we parse.
> 
> > Problem here is that perl is not the only interface that would have this
> > problem.  In fact, I am not sure why libpq doesn't have this problem. 
> 
> No, I wasn't suggesting patching the perl interface; I was suggesting
> changing the backend, ie, adding the \n to the received query in
> postgres.c just before we hand it off to the parser.

I try to avoid hacks like that if I can.  Removing \n from the comment
termination is much clearer and more limited.

> 
> >> BTW, might be a good idea to add \r to that list of "space" characters
> >> so we don't mess up on DOS-style newlines (\r\n).
> 
> > Interesting idea.  I tried that, but the problem is things like this:
> >     xqliteral       [\\](.|\n)
> 
> Hmm, didn't think about what to do with \r inside literals.  I agree,
> it's not worth trying to be smart about those, so I suppose ignoring
> them outside literals would be inconsistent.  Still, how many people
> try to enter newlines within literals?  Adding \r to the whitespace
> set and nothing else might still be a useful compatibility gain.

Added \r to the {space} pattern.

--  Bruce Momjian                        |  http://www.op.net/~candle maillist@candle.pha.pa.us            |  (610)
853-3000+  If your life is a hard drive,     |  830 Blythe Avenue +  Christ can be your backup.        |  Drexel Hill,
Pennsylvania19026
 


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