cube_contains and indexing
I am playing around with the cube extension in contrib and was not able to
get cube_contains to use an index. I was able to get (what I believe to be)
an equivalent @ operation (cubement containment) to use indexes.
So I am either confused about there being a @ equivalent to cube_contains
or cube_contains should be an indexable operation but isn't (or at least
is harder to get to use an index).
Bruno Wolff III <bruno@wolff.to> writes:
I am playing around with the cube extension in contrib and was not able to
get cube_contains to use an index. I was able to get (what I believe to be)
an equivalent @ operation (cubement containment) to use indexes.
So I am either confused about there being a @ equivalent to cube_contains
or cube_contains should be an indexable operation but isn't (or at least
is harder to get to use an index).
It says here (cube.sql.in) that the @ operator *is* cube_contains.
Also, AFAICT both @ and ~ (the commutator operator, cube_contained)
should be equally indexable. Can you show us your test case?
regards, tom lane
On Sat, Aug 17, 2002 at 21:02:43 -0400,
Tom Lane <tgl@sss.pgh.pa.us> wrote:
Bruno Wolff III <bruno@wolff.to> writes:
I am playing around with the cube extension in contrib and was not able to
get cube_contains to use an index. I was able to get (what I believe to be)
an equivalent @ operation (cubement containment) to use indexes.
So I am either confused about there being a @ equivalent to cube_contains
or cube_contains should be an indexable operation but isn't (or at least
is harder to get to use an index).It says here (cube.sql.in) that the @ operator *is* cube_contains.
Also, AFAICT both @ and ~ (the commutator operator, cube_contained)
should be equally indexable. Can you show us your test case?regards, tom lane
A short example is:
cube=> explain select col1 from c where cube_contains('(-78,39),(-77,40)',col1);NOTICE: QUERY PLAN:
Seq Scan on c (cost=0.00..369.30 rows=6195 width=24)
EXPLAIN
cube=> explain select col1 from c where '(-78,39),(-77,40)' @ col1;
NOTICE: QUERY PLAN:
Index Scan using c_index on c (cost=0.00..71.87 rows=19 width=24)
If this really looks like a problem I can provide more details.
I am running 7.2.1 with the cube package added on.
Bruno Wolff III <bruno@wolff.to> writes:
It says here (cube.sql.in) that the @ operator *is* cube_contains.
A short example is:
cube=> explain select col1 from c where cube_contains('(-78,39),(-77,40)',col1);NOTICE: QUERY PLAN:
Seq Scan on c (cost=0.00..369.30 rows=6195 width=24)
EXPLAIN
cube=> explain select col1 from c where '(-78,39),(-77,40)' @ col1;
NOTICE: QUERY PLAN:
Index Scan using c_index on c (cost=0.00..71.87 rows=19 width=24)
Well, yeah. Indexes work with operators, not with functions. This is
a consequence of decisions taken a decade ago at Berkeley: the system
catalogs that show what indexes can do connect *operators* to indexes,
not functions to indexes. Use the operator.
regards, tom lane
On Sun, Aug 18, 2002 at 12:58:39 -0400,
Tom Lane <tgl@sss.pgh.pa.us> wrote:
Well, yeah. Indexes work with operators, not with functions. This is
a consequence of decisions taken a decade ago at Berkeley: the system
catalogs that show what indexes can do connect *operators* to indexes,
not functions to indexes. Use the operator.
Thanks for the explanation of what was happenning.