pg10，pg_suqences和pg_sequence

Move sequences' metadata fields into a newpg_sequencesystem catalog (Peter Eisentraut)

A sequence relation now stores only the fields that can be modified bynextval(),that islast_value,log_cnt,andis_called. Other sequence properties,such as the starting value and increment,are kept in a corresponding row of thepg_sequencecatalog.ALTER SEQUENCEupdates are now fully transactional,implying that the sequence is locked until commit. Thenextval()andsetval()functions remain nontransactional.

The main incompatibility introduced by this change is that selecting from a sequence relation now returns only the three fields named above. To obtain the sequence's other properties,applications must look intopg_sequence. The new system viewpg_sequencescan also be used for this purpose; it provides column names that are more compatible with existing code.

The output ofpsql's\dcommand for a sequence has been redesigned,too.

参考https://www.postgresql.org/docs/10/static/release-10.html