Обсуждение: [GENERAL] Index using in jsonb query

Is there a way to make the following query use some sort of indexing?

select field1,field2 from datatable where (jsonfield#>>'{path1,path2}')::numeric < 1000;

if the '{path1,path2}' part is constant, I'd think you could create an index on (jsonfield #>> '{path1,path2}')::numeric

-- 
john r pierce, recycling bits in santa cruz

On 3/11/2017 3:55 PM, SuperCiccio wrote:

Is there a way to make the following query use some sort of indexing?

select field1,field2 from datatable where (jsonfield#>>'{path1,path2}')::numeric < 1000;

if the '{path1,path2}' part is constant, I'd think you could create an index on (jsonfield #>> '{path1,path2}')::numeric

-- 
john r pierce, recycling bits in santa cruz

On Sun, Mar 12, 2017 at 9:50 AM, SuperCiccio <sc_030268@yahoo.it> wrote:
> But even if I create a specific index
> CREATE INDEX on datatable (((jsonfield#>>'{path1,path2}')::numeric));
> it isn't used in such a query; it is used in this query:
> select field1,field2 from datatable where
> (jsonfield#>>'{path1,path2}')::numeric = 1000;
> Definitely, I didn't find a way to optimize a query that checks a range in a
> json subfield.

Have you checked why it does not use the index? ( how many rows are
returned, stimates etc.. ). Maybe it is not using it because it is
faster ( than using it, index fetches are slower than sequential
fetches ( for the same number of rows ), so for some queries it is
better to not use the index  ) ( specially if you are using them for
small test tables, i.e., for a single page table nothing beats a
sequential scan ).


Francisco Olarte.