sql - 如何在 postgresql 中创建类似于 oracle 的只读 View ？

Question

我想在 PostgreSQL 中创建只读 View 。我们可以在 Oracle 中创建，但不能在 PostgreSQL 中创建。

我试图创建一个只读 View ，但在 READ ONLY 出现语法错误。

CREATE OR REPLACE VIEW VIEW NAME() 
from table names 
where filter condition1=filter 
  condition2 
with READ ONLY; 

但是 READ ONLY 在 PostgreSQL 中不起作用。如何在 PostgreSQL 中创建只读 View ？

Answer 1

我认为 Postgres 没有提供明确定义 View 为只读的方法。

The documentation状态:

Simple views are automatically updatable

但是:

A more complex view that does not satisfy all these conditions is read-only by default.

文档列出了只读 View 的限制:

• A view is automatically updatable if it satisfies all of the following conditions:

• The view must have exactly one entry in its FROM list, which must be a table or another updatable view.

• The view definition must not contain WITH, DISTINCT, GROUP BY, HAVING, LIMIT, or OFFSET clauses at the top level.

• The view definition must not contain set operations (UNION, INTERSECT or EXCEPT) at the top level.

• The view's select list must not contain any aggregates, window functions or set-returning functions.

• Simple views are automatically updatable: the system will allow INSERT, UPDATE and DELETE statements to be used on the view in the same way as on a regular table. A view is automatically updatable if it satisfies all of the following conditions:

• The view must have exactly one entry in its FROM list, which must be a table or another updatable view.

• The view definition must not contain WITH, DISTINCT, GROUP BY, HAVING, LIMIT, or OFFSET clauses at the top level.

• The view definition must not contain set operations (UNION, INTERSECT or EXCEPT) at the top level.

• The view's select list must not contain any aggregates, window functions or set-returning functions

除非您的 View 满足所有 条件，否则它是只读的。如果您有一个想要设为只读的简单 View ，一个(次优)选项是调整其定义，使其违反上述规则之一。

例如，您可以添加一个虚拟的 WITH 子句:

CREATE VIEW myview AS 
WITH dummy AS (SELECT 1)
-- real view definition here