How often is a database update updated in MySQL?

Question

Suppose I have a view in MySQL:

CREATE VIEW blah AS SELECT columnA FROM tableA 

How often is this view updated from the base table, tableA?

Answer 1

Instantly. Views really do not exist as separate copies of data; instead, they exist as instructions for rewriting queries.

That is, when you select columnA from blah , MySQL internally overwrites this as select columnA from tableA .

In systems that support materialized representations, the database is responsible for maintaining their relevance.

(Note that when a query is complex enough, MySQL will only internally materialize the view for the duration of the query. This is an implementation detail and is best considered a defect in the MySQL query optimizer. EXPLAIN can be used to see when this happens, but you will probably notice terrible performance.)