> 2020年2月15日 下午6:06，Pavel Stehule <pavel.steh...@gmail.com> 写道： > > >> postgres=# insert into foo select generate_series(1,10000); >> INSERT 0 10000 >> postgres=# \dt+ foo >> List of relations >> ┌────────┬──────┬───────┬───────┬─────────────┬────────┬─────────────┐ >> │ Schema │ Name │ Type │ Owner │ Persistence │ Size │ Description │ >> ╞════════╪══════╪═══════╪═══════╪═════════════╪════════╪═════════════╡ >> │ public │ foo │ table │ pavel │ session │ 384 kB │ │ >> └────────┴──────┴───────┴───────┴─────────────┴────────┴─────────────┘ >> (1 row) >> >> postgres=# truncate foo; >> TRUNCATE TABLE >> postgres=# \dt+ foo >> List of relations >> ┌────────┬──────┬───────┬───────┬─────────────┬───────┬─────────────┐ >> │ Schema │ Name │ Type │ Owner │ Persistence │ Size │ Description │ >> ╞════════╪══════╪═══════╪═══════╪═════════════╪═══════╪═════════════╡ >> │ public │ foo │ table │ pavel │ session │ 16 kB │ │ >> └────────┴──────┴───────┴───────┴─────────────┴───────┴─────────────┘ >> (1 row) >> >> I expect zero size after truncate. > Thanks for review. > > I can explain, I don't think it's a bug. > The current implementation of the truncated GTT retains two blocks of FSM > pages. > The same is true for truncating regular tables in subtransactions. > This is an implementation that truncates the table without changing the > relfilenode of the table. > > > This is not extra important feature - now this is little bit a surprise, > because I was not under transaction. > > Changing relfilenode, I think, is necessary, minimally for future VACUUM FULL > support. Not allowing relfilenode changes is the current limit. I think can improve on it. But ,This is a bit complicated. so I'd like to know the necessity of this improvement. Could you give me more details?
> > Regards > > Pavel Stehule > > > Wenjing > >> >> Regards >> >> Pavel >> >> >> >> Wenjing >> >> >> >> >> > >> > -- >> > Robert Haas >> > EnterpriseDB: http://www.enterprisedb.com <http://www.enterprisedb.com/> >> > The Enterprise PostgreSQL Company >> >
