altering columns and dropping tables: differences between postgres and oracle

January 11, 2013 — Leave a comment

just noticed another difference between postgres and oracle:


SQL> create table t1 ( a number(10,2 ) );
Table created.
SQL> create view v1 as select a from t1;
View created.
SQL> alter table t1 modify ( a number(11,2));
Table altered.


[postgres] > create table t1 ( a numeric(10,2) );
[postgres] > create view v1 as select a from t1;
[postgres] > alter table t1 alter column a type numeric(11,2);
ERROR:  cannot alter type of a column used by a view or rule
DETAIL:  rule _RETURN on view v1 depends on column "a"

the same is true if you want to drop a table which has a view defined on it:

SQL> drop table t1;
Table dropped.


[postgres] > drop table t1;
ERROR:  cannot drop table t1 because other objects depend on it
DETAIL:  view v1 depends on table t1
HINT:  Use DROP ... CASCADE to drop the dependent objects too.

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