https://www.postgresql.org/docs/current/sql-copy.html

2021
https://blog.skyvia.com/complete-guide-on-how-to-import-and-export-csv-files-to-postgresql/
2020
https://techcommunity.microsoft.com/t5/azure-database-for-postgresql/moving-data-with-postgresql-copy-and-copy-commands/ba-p/1561266
    COPY is server based,
    \COPY is client based (\COPY is a psql feature)
qa
https://dba.stackexchange.com/questions/190780/parsing-copys-binary-format-to-access-a-tsrange
    !!!
????
https://zaiste.net/databases/postgresql/howtos/howto-export-postgresql-query-output-csv/

between dbs
https://www.endpointdev.com/blog/2013/11/copying-rows-between-postgresql
    psql source_database -c 'COPY table TO stdout' | psql target_database -c 'COPY table FROM stdin'

with dblinks
https://stackoverflow.com/questions/36476192/postgresql-copy-transfer-data-from-one-database-to-another
    create extension dblink;
    dblink('yourdbname', 'your query')

insert into t(a, b, c)
select a, b, c from dblink('host=xxx user=xxx password=xxx dbname=xxx', 'select a, b, c from t')
as x(a integer, b integer, c integer)

csv samples
psql-some -c "copy (select * from <table> ...) to stdout with csv header;" > ~/Downloads/file.csv
cat a.csv | psql-some -c "copy <table> from stdin with csv header"