Обсуждение: jsonb and comparison operators
Is it possible to get this query (or a similar one) to use an index?
I want to return all rows that have a value of less than 10. I have arbitrary keys I want to check (not just 'a').
drop table if exists test;
create table test (j jsonb);
insert into test select json_build_object('a', i)::jsonb from generate_series(1, 100000) i;
create index on test using gin(j);
vacuum analyze test;
select * from test where (j->>'a')::int < 10;
I tried
select * from test where j->'a' < 10::json::jsonb;
but didn't seem to use the index.
On Tue, Sep 2, 2014 at 9:38 PM, Joe Van Dyk <joe@tanga.com> wrote: > I want to return all rows that have a value of less than 10. I have > arbitrary keys I want to check (not just 'a'). If you created an expression B-Tree index on 'a' it would work for 'a', but you'd have to use a jsonb literal, not a json/int4 literal. If you want to be able to query every key at the top nesting level of an object, such that all rows are returned with jsonbs that have object values of which in each case one of them is, say, below 10, then that's something that no existing opclass can support. But, why should it be supported? That's a very fuzzy criteria to search on. -- Regards, Peter Geoghegan
On Tue, Sep 2, 2014 at 9:55 PM, Peter Geoghegan <peter.geoghegan86@gmail.com> wrote:
On Tue, Sep 2, 2014 at 9:38 PM, Joe Van Dyk <joe@tanga.com> wrote:If you created an expression B-Tree index on 'a' it would work for
> I want to return all rows that have a value of less than 10. I have
> arbitrary keys I want to check (not just 'a').
'a', but you'd have to use a jsonb literal, not a json/int4 literal.
If you want to be able to query every key at the top nesting level of
an object, such that all rows are returned with jsonbs that have
object values of which in each case one of them is, say, below 10,
Just a particular key specified in the query, not just any of them.
I may want key 'a' one time, and 'b' the next time. Not sure if that's what you meant.
I figured since I could do equality, I should be able to do less than and greater than.
Joe
then that's something that no existing opclass can support. But, why
should it be supported? That's a very fuzzy criteria to search on.
--
Regards,
Peter Geoghegan
jsquery (https://github.com/akorotkov/jsquery) should works for you.
On Wed, Sep 3, 2014 at 8:38 AM, Joe Van Dyk <joe@tanga.com> wrote:
Is it possible to get this query (or a similar one) to use an index?I want to return all rows that have a value of less than 10. I have arbitrary keys I want to check (not just 'a').drop table if exists test;create table test (j jsonb);insert into test select json_build_object('a', i)::jsonb from generate_series(1, 100000) i;create index on test using gin(j);vacuum analyze test;select * from test where (j->>'a')::int < 10;I triedselect * from test where j->'a' < 10::json::jsonb;but didn't seem to use the index.