Storage for multiple variable-length attributes in a single row

Dear all

When ingesting mobility (IoT) data into MobilityDB
https://mobilitydb.com/
we transform very wide (2K attributes) car mobility data of high frequence
(every tenth of a second) from flat format (e.g. CSV) into MobilityDB
format in which there is a single record per trip and each of the signals
is transformed into a temporal attribute (tbool, tint, tfloat, ttext,
tgeompoint, tgeogpoint), which are temporal extensions of the corresponding
PostgreSQL/PostGIS base types (bool, int, float, text, geometry,
geography). All temporal types are stored using extended format, e.g.,
CREATE TYPE tfloat (
internallength = variable,
[...]
storage = extended,
alignment = double,
[...]
);

Given that each temporal value can be very wide (on average 30K
timestamped points/floats/text/... per trip) our first question is
* Is extended the right storage for this ?

Our second question is how all the 2K temporal attributes are stored, which
may be
* on a single table space
* in one table space per attribute
which in other words, relates to the question row vs column storage.

Many thanks for your insight

Esteban