On Mon, Jun 8, 2020 at 10:16 PM Ashutosh Bapat
wrote:
> I know one project where they used PostgreSQL code base to detect
> "robust plans". https://dsl.cds.iisc.ac.in/projects/PICASSO/. Some of
> the papers cited in https://www.vldb.org/pvldb/vldb2010/papers/D01.pdf
> describe the idea.
>
In sh
On Fri, Jun 5, 2020 at 2:30 PM Pavel Stehule
wrote:
>
>
> pá 5. 6. 2020 v 8:19 odesílatel David Rowley
> napsal:
>
>> On Mon, 1 Jun 2020 at 01:24, Andy Fan wrote:
>> > The one-line fix describe the exact idea in my mind:
>> >
>> > +++ b/src/backend/optimizer/path/costsize.c
>> > @@ -730,6 +730,
I know one project where they used PostgreSQL code base to detect
"robust plans". https://dsl.cds.iisc.ac.in/projects/PICASSO/. Some of
the papers cited in https://www.vldb.org/pvldb/vldb2010/papers/D01.pdf
describe the idea.
In short, the idea is to annotate a plan with a "bandwidth" i.e. how
doe
pá 5. 6. 2020 v 8:19 odesílatel David Rowley napsal:
> On Mon, 1 Jun 2020 at 01:24, Andy Fan wrote:
> > The one-line fix describe the exact idea in my mind:
> >
> > +++ b/src/backend/optimizer/path/costsize.c
> > @@ -730,6 +730,13 @@ cost_index(IndexPath *path, PlannerInfo *root,
> double loop_c
On Mon, 1 Jun 2020 at 01:24, Andy Fan wrote:
> The one-line fix describe the exact idea in my mind:
>
> +++ b/src/backend/optimizer/path/costsize.c
> @@ -730,6 +730,13 @@ cost_index(IndexPath *path, PlannerInfo *root, double
> loop_count,
>
> cpu_run_cost += cpu_per_tuple * tuples_fetched
>
>
>
> Why will the (a, c) be choose? If planner think a = x has only 1 row ..
>
I just did more research and found above statement is not accurate,
the root cause of this situation is because IndexSelectivity = 0. Even
through I
don't think we can fix anything here since IndexSelectivity is cal
This thread is a follow-up of thread [1] where I don't have a good writing
to
describe the issue and solution in my mind. So I start this thread to fix
that
and also enrich the topic by taking the advices from Ashutosh, Tomas and
Tom.
Inaccurate statistics is not avoidable and can cause lots of is
