perf: eliminate program and program stage table joins in tracker event queries DHIS2-20922

[teleivo]

Eliminate program and programstage table joins from tracker event queries when the respective parameter is known. The columns (uid, code, name, attributeValues) are already available from the Java objects loaded during request validation, so we populate them directly in the row mapper instead of joining the tables.

Same approach as #22920 for tracked entities and #22972 for enrollments.

The program parameter is mandatory for /api/tracker/events, so the program join is always eliminated. The programstage join is eliminated when a specific program stage is requested.

Before:

select
    ...
    p.uid as p_uid, p.code as p_code, p.name as p_name,
    p.attributevalues as p_attributevalues,
    ps.uid as ps_uid, ps.code as ps_code, ps.name as ps_name,
    ps.attributevalues as ps_attributevalues,
    ...
    p.type as p_type,
    ...
from trackerevent ev
inner join enrollment en on en.enrollmentid = ev.enrollmentid
inner join program p on p.programid = en.programid
inner join programstage ps on ps.programstageid = ev.programstageid
...
where
    p.programid = 1150449
    and ps.programstageid in (860005, 1150450, 859998)

After (with program and program stage known):

select
    ...
    ev.eventid as ev_id, ev.status as ev_status,
    ...
from trackerevent ev
inner join enrollment en on en.enrollmentid = ev.enrollmentid
...
where
    en.programid = 1150449
    and ev.programstageid = 860005

Performance

Database

Sierra Leone DB with ~10M tracked entities, ~32M events. EXPLAIN ANALYZE (4 warmup runs) and pgbench (1 client, 30s) on the base event query (program=ur1Edk5Oe2n&pageSize=3).

Metric	Baseline (all joins)	No program join	No program+stage joins
Planning Time	19.2 ms	16.7 ms (-13%)	18.2 ms (-5%)
pgbench TPS	57.2	65.2 (+14%)	71.7 (+25%)
pgbench latency	17.5 ms	15.3 ms (-12%)	13.9 ms (-20%)

Execution time unchanged (~11ms). The gains are in planning time and sustained throughput. With both joins eliminated, pgbench throughput improves by 25%.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud