perf: eliminate program table join in single event queries [DHIS2-20891]

[enricocolasante]

Eliminate program and programstage table joins from single 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.

Similar approach as #23044 for tracker events.

The program parameter is mandatory for /api/tracker/events, so the program join is always eliminated and, in the case of single events, a program of type WITHOUT_REGISTRATION only has one programstage, hence also the program stage join can be eliminated.

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 singleevent ev
inner join program p on p.programid = en.programid
inner join programstage ps on ps.programstageid = ev.programstageid
...
where
    p.programid = 1150449

After (with program known):

select
    ...
    ev.eventid as ev_id, ev.status as ev_status,
    ...
from singleevent ev
...
where
    ev.programstageid = 860005

Performance

Database

• Smoke test

Request	Base p95	Cand p95	Diff
Go to first page of program VBqh0ynB2wv	10ms	10ms	+0%
Go to second page of program VBqh0ynB2wv	10ms	10ms	+0%
Search single events assigned to any user in program VBqh0ynB2wv	6ms	7ms	+17%
Search single events in date interval in program VBqh0ynB2wv	22ms	22ms	+0%
Search single events not assigned to a user in program VBqh0ynB2wv	10ms	10ms	+0%

• Load test

Request	Base p95	Cand p95	Diff
Go to first page of program VBqh0ynB2wv	11ms	10ms	-9%
Go to second page of program VBqh0ynB2wv	11ms	10ms	-9%
Search single events assigned to any user in program VBqh0ynB2wv	7ms	7ms	+0%
Search single events in date interval in program VBqh0ynB2wv	10ms	10ms	+0%
Search single events not assigned to a user in program VBqh0ynB2wv	10ms	10ms	+0%

No regressions and no visible improvement

[teleivo]

use a text block or single line

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
7.2% Duplication on New Code

See analysis details on SonarQube Cloud