> 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. Regards Pavel Stehule > > Wenjing > > > Regards > > Pavel > > >>> >>> Wenjing >>> >>> >>> >>> >>> > >>> > -- >>> > Robert Haas >>> > EnterpriseDB: http://www.enterprisedb.com >>> > The Enterprise PostgreSQL Company >>> >>> >
