Tom Lane wrote:
Simon Riggs <[EMAIL PROTECTED]> writes:
On Thu, 2008-06-26 at 12:36 -0400, Robert Haas wrote:
It's my understanding that the philosophy of the PGDG in the past has
been to avoid putting any kind of hints into the system, focusing
rather an improving the planning of queries.
I
Andres Freund <[EMAIL PROTECTED]> writes:
>> The only way it could do that would be by interchanging the order of the
>> left and inner joins, ie (ab left join bc) join cd; which would change
>> the results.
> My knowledge about the implementation side of relational databases is quite
> limited,
Hi,
On Thursday 26 June 2008 04:36:09 Tom Lane wrote:
> Andres Freund <[EMAIL PROTECTED]> writes:
> > SELECT *
> > FROM
> > ab LEFT OUTER JOIN (
> > bc JOIN cd
> > ON bc.c = cd.d
> > )
> > ON ab.b = bc.b
> >
> > WHERE
> > ab.a = 2
> >
> > As ab.a = 2
Tom Lane wrote:
Ron Mayer <[EMAIL PROTECTED]> writes:
Couldn't the planner itself make a good guess if it should
keep trying based on the estimated cost?
if (the_best_plan_I_found_so_far_looks_like_itll_take_an_hour)
keep_optimizing_for_a_few_minutes
if (the_best_plan_I_found_so_far_looks_
Ron Mayer <[EMAIL PROTECTED]> writes:
> Couldn't the planner itself make a good guess if it should
> keep trying based on the estimated cost?
> if (the_best_plan_I_found_so_far_looks_like_itll_take_an_hour)
>keep_optimizing_for_a_few_minutes
> if (the_best_plan_I_found_so_far_looks_like_itll_t
Simon Riggs wrote:
IMHO we should have a single parameter which indicates how much planning
time we consider acceptable for this query. e.g.
optimization_level = 2 (default), varies 1-3
Couldn't the planner itself make a good guess if it should
keep trying based on the estimated cost?
if (th
On Thu, 2008-06-26 at 12:57 -0400, Tom Lane wrote:
> Simon Riggs <[EMAIL PROTECTED]> writes:
> > On Thu, 2008-06-26 at 12:36 -0400, Robert Haas wrote:
> >> It's my understanding that the philosophy of the PGDG in the past has
> >> been to avoid putting any kind of hints into the system, focusing
>
Simon Riggs <[EMAIL PROTECTED]> writes:
> On Thu, 2008-06-26 at 12:36 -0400, Robert Haas wrote:
>> It's my understanding that the philosophy of the PGDG in the past has
>> been to avoid putting any kind of hints into the system, focusing
>> rather an improving the planning of queries.
> It's not a
On Thu, 2008-06-26 at 12:36 -0400, Robert Haas wrote:
> > IMHO we should have a single parameter which indicates how much planning
> > time we consider acceptable for this query. e.g.
> >
> > optimization_level = 2 (default), varies 1-3
> >
> > Most automatic optimisation systems allow this kind
> IMHO we should have a single parameter which indicates how much planning
> time we consider acceptable for this query. e.g.
>
> optimization_level = 2 (default), varies 1-3
>
> Most automatic optimisation systems allow this kind of setting, whether
> it be a DBMS, or compilers (e.g. gcc).
It's
[EMAIL PROTECTED] (Simon Riggs) writes:
> On Wed, 2008-06-25 at 23:34 -0400, Robert Haas wrote:
>> I can predict that Tom will say that the planning time it would take
>> to avoid this problem isn't justified by the number of queries that it
>> would improve.
>
>> That's possible, but it's unfort
On Wed, 2008-06-25 at 23:34 -0400, Robert Haas wrote:
> I can predict that Tom will say that the planning time it would take
> to avoid this problem isn't justified by the number of queries that it
> would improve.
> That's possible, but it's unfortunate that there's no
> way to fiddle with the
"Robert Haas" <[EMAIL PROTECTED]> writes:
> I can predict that Tom will say that the planning time it would take
> to avoid this problem isn't justified by the number of queries that it
> would improve.
Took the words right out of my mouth ;-)
It would be *possible* to do this sort of thing, but
>> SELECT * FROM ab LEFT OUTER JOIN (bc JOIN cd ON bc.c = cd.d) ON ab.b = bc.b
>> WHERE ab.a = 2
>> As ab.a = 2 occurs only once in ab one would expect that it just does an
>> index scan on bc for ab.b = bc.b.
>
> The only way it could do that would be by interchanging the order of the
> le
Andres Freund <[EMAIL PROTECTED]> writes:
> SELECT *
> FROM
> ab LEFT OUTER JOIN (
> bc JOIN cd
> ON bc.c = cd.d
> )
> ON ab.b = bc.b
> WHERE
> ab.a = 2
> As ab.a = 2 occurs only once in ab one would expect that it just does an
Hi,
After pondering on the problem for quite some time and discussing it on IRC
with RhodiumToad I thought the most sensible thing is to post the problem
here (as RhodiumToad suggested as well).
The original (although already quite reduced) problematic query and the
related plan:
http://anaraz
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