Обсуждение: When the locially dropped column is also physically dropped
Hi,<br />I have dropped a column (say column name is 'A') from the relation R. By setting the attisdropped as true in thepg_catalog.pg_attribute table. But the column is dropped locially not the physically. Can you please tell me when thiscolumn will be physically also dropped. Is this column is automatically physically dropped? or I have to run some commandto dropped it physically. <br /><br />Thanks,<br />Rupesh Bajaj<br />
"rupesh bajaj" <rupesh.bajaj@gmail.com> writes: > Hi, > I have dropped a column (say column name is 'A') from the relation R. By > setting the attisdropped as true in the pg_catalog.pg_attribute table. But > the column is dropped locially not the physically. Can you please tell me > when this column will be physically also dropped. Is this column is > automatically physically dropped? or I have to run some command to dropped > it physically. These kinds of questions are best sent to pgsql-general instead of -hackers. The column won't be dropped physically until you execute one of the commands that rewrites the table entirely. "CLUSTER" and "ALTER TABLE ALTER column TYPE type" are the two popular ones. -- Gregory Stark EnterpriseDB http://www.enterprisedb.com
On Apr 27, 2007, at 12:35 PM, Gregory Stark wrote: >> I have dropped a column (say column name is 'A') from the relation >> R. By >> setting the attisdropped as true in the pg_catalog.pg_attribute >> table. But >> the column is dropped locially not the physically. Can you please >> tell me >> when this column will be physically also dropped. Is this column is >> automatically physically dropped? or I have to run some command to >> dropped >> it physically. > > These kinds of questions are best sent to pgsql-general instead of - > hackers. > > The column won't be dropped physically until you execute one of the > commands > that rewrites the table entirely. "CLUSTER" and "ALTER TABLE ALTER > column TYPE > type" are the two popular ones. UPDATE SET field1 = field1; would also work, right? -- Jim Nasby jim@nasby.net EnterpriseDB http://enterprisedb.com 512.569.9461 (cell)
Jim Nasby wrote: > On Apr 27, 2007, at 12:35 PM, Gregory Stark wrote: >> The column won't be dropped physically until you execute one of the >> commands >> that rewrites the table entirely. "CLUSTER" and "ALTER TABLE ALTER >> column TYPE >> type" are the two popular ones. > > UPDATE SET field1 = field1; would also work, right? Well, yes, except that it will bloat the table. If you wanted to physically drop the column to save space, you're not going to be happy with that. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com