From: Bruce Momjian <pgman@candle.pha.pa.us>
To: magnus.enbom@rockstorm.se
Cc: pgsql-sql@postgresql.org
Subject: Re: LIMIT 1 FOR UPDATE or FOR UPDATE LIMIT 1?
Date: Sun, 25 Aug 2002 20:31:12 -0400 (EDT)
Message-ID: <200208260031.g7Q0VCC24924@candle.pha.pa.us> (raw)
In-Reply-To: <20020405160833.A917@ford.rockstorm.se>
I found this email from April. It properly points out that our
LIMIT/FOR UPDATE ordering doesn't match MySQL's, and MySQL's looks more
correct, specifically that the FOR UPDATE is after the LIMIT. Our
grammar is:
| select_clause sort_clause opt_for_update_clause opt_select_limit
How do we want to deal with this? I tried allowing both orderings with
the attached patch but got:
bison -y -d gram.y
conflicts: 4 shift/reduce, 5 reduce/reduce
---------------------------------------------------------------------------
Magnus Enbom wrote:
> Hi,
>
> I've just been hit by a small but annoying difference between postgres(7.2)
> and mysql(4.x).
> In postgresql you do:
>
> SELECT * FROM table FOR UPDATE LIMIT 1;
>
> and in mysql you do:
>
> SELECT * FROM table LIMIT 1 FOR UPDATE;
>
> Is it possible for postgres to accept the mysql syntax as well?
> It's not that many databases that implement LIMIT, so it would be nice if the
> ones that do have the same syntax(or can accept each others variants).
>
> -- Magnus
>
> ---------------------------(end of broadcast)---------------------------
> TIP 2: you can get off all lists at once with the unregister command
> (send "unregister YourEmailAddressHere" to majordomo@postgresql.org)
>
--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073
Attachments:/bjm/diff (text/plain, 976B) download
Index: gram.y
===================================================================
RCS file: /cvsroot/pgsql-server/src/backend/parser/gram.y,v
retrieving revision 2.360
diff -c -r2.360 gram.y
*** gram.y 19 Aug 2002 15:08:47 -0000 2.360
--- gram.y 26 Aug 2002 00:29:24 -0000
***************
*** 4114,4123 ****
--- 4114,4135 ----
nth(0, $4), nth(1, $4));
$$ = $1;
}
+ | select_clause sort_clause opt_select_limit opt_for_update_clause
+ {
+ insertSelectOptions((SelectStmt *) $1, $2, $4,
+ nth(0, $3), nth(1, $3));
+ $$ = $1;
+ }
| select_clause for_update_clause opt_select_limit
{
insertSelectOptions((SelectStmt *) $1, NIL, $2,
nth(0, $3), nth(1, $3));
+ $$ = $1;
+ }
+ | select_clause opt_select_limit for_update_clause
+ {
+ insertSelectOptions((SelectStmt *) $1, NIL, $3,
+ nth(0, $2), nth(1, $2));
$$ = $1;
}
| select_clause select_limit
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To: pgsql-sql@postgresql.org
Cc: pgman@candle.pha.pa.us, magnus.enbom@rockstorm.se
Subject: Re: LIMIT 1 FOR UPDATE or FOR UPDATE LIMIT 1?
In-Reply-To: <200208260031.g7Q0VCC24924@candle.pha.pa.us>
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