#Materialize tables update#

In IBM DB2, they are called 'materialized query tables'. Materialized views are also supported in Sybase SQL Anywhere. In contrast, in a normal view, it's typically only possible to exploit indexes on columns that come directly from (or have a mapping to) indexed columns in the base tables often this functionality is not offered at all.Д¬REATE VIEW MV_MY_VIEW WITH SCHEMABINDING AS SELECT COL1, SUM ( COL2 ) AS TOTAL FROM GROUP BY COL1 GO CREATE UNIQUE CLUSTERED INDEX XV ON MV_MY_VIEW ( COL1 ) Stream processing frameworks ДЄpache Kafka (since v0.10.2), Apache Spark (since v2.0), and Materialize all support materialized views on streams of data. In a materialized view, indexes can be built on any column. Materialized views find use especially in data warehousing scenarios, where frequent queries of the actual base tables can be expensive. This enables much more efficient access, at the cost of extra storage and of some data being potentially out-of-date. A materialized view takes a different approach: the query result is cached as a concrete ('materialized') table (rather than a view as such) that may be updated from the original base tables from time to time.

#Materialize tables update#

Whenever a query or an update addresses an ordinary view's virtual table, the DBMS converts these into queries or updates against the underlying base tables. In any database management system following the relational model, a view is a virtual table representing the result of a database query. Materialized views which store data based on remote tables were also known as snapshots (deprecated Oracle terminology). As with other forms of precomputation, database users typically use materialized views for performance reasons, i.e.

This is a form of caching the results of a query, similar to memoization of the value of a function in functional languages, and it is sometimes described as a form of precomputation. The process of setting up a materialized view is sometimes called materialization.

For example, it may be a local copy of data located remotely, or may be a subset of the rows and/or columns of a table or join result, or may be a summary using an aggregate function. In computing, a materialized view is a database object that contains the results of a query.