$ psql postgres
psql (13.0)
WARNING: Console code page (437) differs from Windows code page (1252)
         8-bit characters might not work correctly. See psql reference
         page "Notes for Windows users" for details.
Type "help" for help.

postgres=# create function check_estimated_rows(text) returns table (estimated int, actual int)
postgres-# language plpgsql as
postgres-# $$
postgres$# declare
postgres$#     ln text;
postgres$#     tmp text[];
postgres$#     first_row bool := true;
postgres$# begin
postgres$#     for ln in
postgres$#         execute format('explain analyze %s', $1)
postgres$#     loop
postgres$#         if first_row then
postgres$#             first_row := false;
postgres$#             tmp := regexp_match(ln, 'rows=(\d*) .* rows=(\d*)');
postgres$#             return query select tmp[1]::int, tmp[2]::int;
postgres$#         end if;
postgres$#     end loop;
postgres$# end;
postgres$# $$;
CREATE FUNCTION
postgres=# CREATE STATISTICS tst;
ERROR:  syntax error at or near ";"
LINE 1: CREATE STATISTICS tst;
                             ^
postgres=# CREATE STATISTICS tst ON a, b;
ERROR:  syntax error at or near ";"
LINE 1: CREATE STATISTICS tst ON a, b;
                                     ^
postgres=# CREATE STATISTICS tst FROM sometab;
ERROR:  syntax error at or near "FROM"
LINE 1: CREATE STATISTICS tst FROM sometab;
                              ^
postgres=# CREATE STATISTICS tst ON a, b FROM nonexistent;
ERROR:  relation "nonexistent" does not exist
postgres=# CREATE STATISTICS tst ON a, b FROM pg_class;
ERROR:  column "a" does not exist
postgres=# CREATE STATISTICS tst ON relname, relname, relnatts FROM pg_class;
ERROR:  duplicate column name in statistics definition
postgres=# CREATE STATISTICS tst ON relnatts + relpages FROM pg_class;
server closed the connection unexpectedly
        This probably means the server terminated abnormally
        before or while processing the request.
The connection to the server was lost. Attempting reset: Failed.