What does the `width` field mean in PostgreSQL's EXPLAIN?

Question

For example, from the EXPLAIN documentation:

EXPLAIN SELECT * FROM tenk1;

                         QUERY PLAN
-------------------------------------------------------------
 Seq Scan on tenk1  (cost=0.00..458.00 rows=10000 width=244)

What does width=244 mean?

Answer 1

This is the "Estimated average width (in bytes) of rows output by this plan node"

Basically each row returned will be 244 bytes.

See Explain for more details.