RE: [HACKERS] Lex and things...

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От Ansley, Michael
Тема RE: [HACKERS] Lex and things...
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Msg-id 1BF7C7482189D211B03F00805F8527F70ED128@S-NATH-EXCH2
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Список pgsql-hackers
Sorry, I forgot to mention in the previous mail: I sent patches to the
patches mailing list (available from the web server), which patch psql, and
libpq, and scan.l (except for you patch).  The were sent at the beginning of
this month, so maybe get them, and see how they work for you.

>> -----Original Message-----
>> From: Ansley, Michael [mailto:Michael.Ansley@intec.co.za]
>> Sent: Tuesday, August 24, 1999 12:57 PM
>> To: 'Leon'; 'pgsql-hackers@postgresql.org'
>> Subject: RE: [HACKERS] Lex and things...
>> 
>> 
>> >> > Shot, Leon.  The patch removes the #define 
>> YY_USES_REJECT from scan.c,
>> which
>> >> > means we now have expandable tokens.  Of course, it 
>> also removes the
>> >> > scanning of "embedded minuses", which apparently causes 
>> the optimizer
>> to
>> >> > unoptimize a little. 
>> >> 
>> >> Oh, no. Unary minus gets to grammar parser and there is 
>> recognized as
>> >> such. Then for numeric constants it becomes an *embedded* minus in
>> >> function doNegate. So unary minus after parser in numeric 
>> constants
>> >> is embedded minus, as it was earlier before patch. In other words,
>> >> I can see no change in representation of grammar after patching.
>> Great.
>> >> 
>> >> > However, the next step is attacking the limit on the
>> >> > size of string literals.  These seemed to be wired to 
>> YY_BUF_SIZE, or
>> >> > something.  Is there any reason for this?
>> >> 
>> >> Hmm. There is something going on to remove fixed length limits 
>> >> entirely, maybe someone is already doing something to lexer in
>> >> that respect? If no, I could look at what can be done there.
>> Yes, me.  I've removed the query string limit from psql, 
>> libpq, and as much
>> of the backend as I can see.  I have done some (very) 
>> preliminary testing,
>> and managed to get a 95kB query to execute.  However, the 
>> two remaining
>> problems that I have run into so far are token size (which 
>> you have just
>> removed, many thanks ;-), and string literals, which are 
>> limited, it seems
>> to YY_BUF_SIZE (I think).
>> 
>> You see, if I can get the query string limited removed, 
>> perhaps someone who
>> knows a bit more than I do will do something like, hmmm, 
>> say, remove the
>> block size limit from tuple size... hint, hint... anybody...
>> 
>> MikeA
>> 
>> 
>> >> 
>> >> -- 
>> >> Leon.
>> >> 
>> 
>> ************
>> 


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