Is ALTER TABLE blocking?

Question

When you run an alter table statement, PostgreSQL will update the table structure and there is no locking unless you do something that needs to alter existing rows. 21 апр. 2016 г.

Does ALTER TABLE lock table Oracle?

Yes, any lock acquiring on that table will fail if it's in that state. Run ALTER TABLE table_name ENABLE TABLE LOCK so you can acquire table locks again.

What does the ALTER TABLE cause do?

ALTER TABLE changes the structure of a table. For example, you can add or delete columns, create or destroy indexes, change the type of existing columns, or rename columns or the table itself. You can also change characteristics such as the storage engine used for the table or the table comment.

Does ALTER TABLE remove data?

No it will not erase your data. It will add a column and all the existing data will be assigned null values in this column.

Does ALTER TABLE change data?

The basic syntax of an ALTER TABLE command to change the DATA TYPE of a column in a table is as follows. ALTER TABLE table_name MODIFY COLUMN column_name datatype; The basic syntax of an ALTER TABLE command to add a NOT NULL constraint to a column in a table is as follows.

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