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Can we update view in PostgreSQL?
An updatable view may contain both updatable and non-updatable columns. If you try to insert or update a non-updatable column, PostgreSQL will raise an error. In case you have a WHERE condition in the defining query of a view, you still can update or delete the rows that are not visible through the view.
How does select for update work Postgres?
The select for update acquires a ROW SHARE LOCK on a table. This lock conflicts with the EXCLUSIVE lock needed for an update statement, and prevents any changes that could happen concurrently. All the locks will be released when the transaction ends.
Does updating a view update the table?
Yes. The data “in” a view has no existence independent from the tables that make up the view. The view is, in essence, a stored SELECT statement that masquerades as a table. The data is stored in the original tables and only “assembled” into the view when you want to look at it.
Does select for UPDATE block read?
A SELECT FOR UPDATE reads the latest available data, setting exclusive locks on each row it reads.
When to update a table in posgresql?
When you execute an update operation such as INSERT, UPDATE or DELETE, PosgreSQL will convert this statement into the corresponding statement of the underlying table. In case you have a WHERE condition in the defining query of a view, you still can update or delete the rows that are not visible through the view.
Why do I need a SELECT statement in PostgreSQL?
A regular select statement does not give you enough protection if you want to query data and make a change in the database related to it. Other transactions can update or delete the data you just queried. PostgreSQL offers additional select statements that lock on read and provide an extra layer of safety.
If only one CPU can be active at a time, it is pointless to scale your servers. For this purpose, in PostgreSQL there is a mechanism for selecting only rows that are not locked. The select for update skip lockedis a statement that allows you to query rows that have no locks.
When is a PostgreSQL view an updatable view?
A PostgreSQL view is updatable when it meets the following conditions: The defining query of the view must have exactly one entry in the FROM clause, which can be a table or another updatable view.