To select all the matching data:
```
create table t1 (id integer primary key, ts not null unique, a, b, c);
create table t2 (id integer primary key, ts not null unique, d, e, f);
select *
from t1, t2
where t2.id == (
select id2
from (
select delta,
id2
from (
select id as id2,
ts - t1.ts as delta
from t2
where ts >= t1.ts
order by ts
limit 1
)
union
select delta,
id2
from (
select id as id2,
t1.ts - ts as delta
from t2
where ts <= t1.ts
order by ts desc
limit 1
)
)
)
;
```