Index on If missing field

I create an index on If Missing(Filed)

CREATE INDEX idx_drt_benfMissing_1 ON dataRT(ifmissing(beneficiaries, false)) WHERE (type = “Policy”) WITH { “defer_build”:true }

After that I am running query it’s still taking more time

select Count(meta().id) from dataRT where type_=“Policy” and beneficiaries is missing

Please suggest some best way. for filed missing count and records.

If you need count type_ = “Policy”
CREATE INDEX ix1 ON dataRT(type_);
select Count(meta().id) from dataRT where type_=“Policy”

Count on basis of missing thing,
Ifmissing condition i want to put in where clause.

select Count(meta().id) from dataRT where type_=“Policy” and ifmissing( beneficiaries , false) = false;

Also try this
CREATE INDEX ix1 ON dataRT(type_) WHERE beneficiaries IS MISSING;
select Count(meta().id) from dataRT where type_=“Policy” AND beneficiaries IS MISSING;

Indexing is also required for selecting fields? or only for where clause fields?