The IATA filter ran a correlated EXISTS over packets/observations with
ILIKE, which skipped the iata index and took ~7s live. Keep a small
channel_iatas table at ingest (like node_iatas) and filter against it.
Also honor the iatas= param so multi-site regions stop getting the
global list. Filter now ages out with packet retention rather than
matching any retained packet.
Quiet sites probed hundreds of thousands of packets to fill a page.
Walk idx_observations_iata_heard per requested site and dedup instead.
Filtered lists now order by site-local recency; the cursor follows.
text[] from string_to_array can't match the CHAR(3) indexes and hides
the values from the planner. Handlers already have a slice; stop
joining to CSV in the store layer and pass a typed array everywhere.
MrAlders0n