On Mon, Jul 13, 2009 at 07:06:40PM +0100, Simon Riggs wrote:
On Mon, 2009-07-13 at 13:33 -0400, Tom Lane wrote:
It's hard to believe
this sort of case comes up often enough to justify the cycles that would
be expended (on *every* join query) to try to recognize it.
Yeh, damn ORMs seem to
In some cases, we have SQL being submitted that has superfluous
self-joins. An example would be
select count(*)
from foo1 a, foo1 b
where a.c1 = b.c1 /* PK join */
and a.c2 = 5
and b.c2 = 10;
We can recognise that a and b are the same table because they are
joined on the PK. PK is never
Simon Riggs si...@2ndquadrant.com wrote:
select count(*)
from foo1 a, foo1 b
where a.c1 = b.c1 /* PK join */
You may well ask who would be stupid enough to write SQL like that.
The answer is of course that it is automatically generated by an
ORM.
We had to do something like that to
Simon Riggs si...@2ndquadrant.com writes:
In some cases, we have SQL being submitted that has superfluous
self-joins. An example would be
select count(*)
from foo1 a, foo1 b
where a.c1 = b.c1 /* PK join */
and a.c2 = 5
and b.c2 = 10;
You may well ask who would be stupid enough to
Kevin Grittner kevin.gritt...@wicourts.gov writes:
Simon Riggs si...@2ndquadrant.com wrote:
select count(*)
from foo1 a, foo1 b
where a.c1 = b.c1 /* PK join */
We had to do something like that to get acceptable performance from
Sybase ASE.
Writing a join for a single-table query? Why,
On Mon, 2009-07-13 at 13:33 -0400, Tom Lane wrote:
Simon Riggs si...@2ndquadrant.com writes:
In some cases, we have SQL being submitted that has superfluous
self-joins. An example would be
select count(*)
from foo1 a, foo1 b
where a.c1 = b.c1 /* PK join */
and a.c2 = 5
and
On Mon, Jul 13, 2009 at 1:33 PM, Tom Lanet...@sss.pgh.pa.us wrote:
Simon Riggs si...@2ndquadrant.com writes:
In some cases, we have SQL being submitted that has superfluous
self-joins. An example would be
select count(*)
from foo1 a, foo1 b
where a.c1 = b.c1 /* PK join */
and a.c2 = 5
and
Tom Lane t...@sss.pgh.pa.us wrote:
Writing a join for a single-table query? Why, in heavens name?
(Or have you mercifully blotted the details from your memory?)
Actually, I had only the vaguest recollection of why, but I found an
email where I was explaining the problem to Sybase.
On Jul 13, 2009, at 1:06 PM, Simon Riggs wrote:
Not just because of this but I wonder if we might benefit from an
optimizer setting specifically aimed at the foolishnesses of
automatically generated SQL.
+1. And it's not just ORMs that do stupid things, I've seen crap like
this come out of
On Mon, Jul 13, 2009 at 3:48 PM, decibeldeci...@decibel.org wrote:
On Jul 13, 2009, at 1:06 PM, Simon Riggs wrote:
Not just because of this but I wonder if we might benefit from an
optimizer setting specifically aimed at the foolishnesses of
automatically generated SQL.
+1. And it's not
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