sql - Inner join order by performance issue in Android 2.3 -

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i have used sql select query in android app works fine on newer versions of android i.e takes 30 40 seconds on samsung galaxy tab( android 4.0.3) retreive data sqlite database, on device older version of android 2.3 takes 18 minutes retreive data. if remove "order x_unitperson.unitseq" performance not decreases on android 2.3. how can increase performance on android 2.3 without removing order clause.

my sql is:

select person_id,        commander,        citizen,        rank,        given,        surname,        isor,    (select group_concat(name_short, '\n')    units    inner join      (select *       x_unitperson       person_id = people.person_id       order x_unitperson.unitseq) xunits    units.unit_id = xunits.unit_id) name_short,    (select fname    photos    person_id = people.person_id) fname people order surname,          given

i not familiar sqlite optimiser, if correlated subquery rewritten join optimisers create same execution plan both queries, , not sure if sqlite 1 of these, may worth converting query use joins rather correlated subqueries, see if avoids:

select  people.person_id,         people.commander,         people.citizen,         people.rank,         people.given,         people.surname,         people.isor,         ns.name_short,         photos.fnane    people         left join         (   select  units.person_id, group_concat(name_short, '\n') name_short                units                     inner join                     (   select  unit_id, name_short                            x_unitperson                         order unit_id, x_unitperson.unitseq                     ) xunits                         on units.unit_id = xunits.unit_id             group units.person_id         ) ns             on ns.person_id = people.person_id         left join photos             on photos.person_id = people.person_id order people.surname, people.given;

in addition (using can gather schema) have removed select * query, bad practice in production code, have prefixed column references table name/alias, again safeguards query against future schema changes.


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