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92 High-Function Business Intelligence in e-business

2.11 Materialized view limitations

The limitations applying to materialized views fall into the categories and

subcategories shown in Figure 2-15.

Figure 2-15 Materialized view limitation categories

The following sections describe the restrictions in each of the above categories.

2.11.1 REFRESH DEFERRED and REFRESH IMMEDIATE

The following fullselect restrictions apply to both REFRESH DEFERRED and

REFRESH IMMEDIATE materialized views:

򐂰 References to a materialized view, declared temporary table, or typed table in

any FROM clause.

򐂰 References to a view where the fullselect of the view violates any of the listed

restrictions on the fullselect of a materialized view.

򐂰 Expressions that are a reference type or DATALINK type (or distinct type

based on these types).

򐂰 Functions that have external action.

򐂰 Functions written in SQL.

Materialized VIew Limitations

Restrictions that ONLY apply to

REFRESH IMMEDIATE materialized views

and

REFRESH DEFERRED materialized views

associated with a staging table

General restrictions

Restrictions related to the requirement

that there can be NO DUPLICATES in the

materialized view

Restrictions when

there is no GROUP

BY clause defined

Restrictions that apply to

BOTH

REFRESH IMMEDIATE

and

REFRESH DEFERRED

materialized views

Restrictions when

a GROUP BY

clause is defined