Last updated: Nov 26, 2024
When you create a cache in Data Virtualization, you must consider certain restrictions.
Caching in Data Virtualization is subject to the following restrictions:
- You can't use the
clause.fetch first n rows
- You can't use the
clause.order by
- You can't use
statements that use theselect
clause.with
- Data types that are not supported:
- BINARY (BINARY is not supported; however, VARBINARY is supported)
- CHAR FOR BIT DATA, VARCHAR FOR BIT DATA
- DECFLOAT
- GRAPHIC, VARGRAPHIC
- LOB types (BLOB, CLOB, DBCLOB)
- LONG VARCHAR, LONG VARGRAPHIC (These types are deprecated in Db2®)
- TIME
- XML
Data Virtualization caching is built on Db2 Big SQL capabilities that involve Hadoop MQTs. The following restrictions apply.
- You must be aware of restrictions in the
statement. For more information, see CREATE TABLE (HADOOP) statement in the Db2 Big SQL product documentation.CREATE TABLE (HADOOP)
Data Virtualization caching is also built on Db2 MQT capabilities. The following Db2 MQT restrictions apply. For more information, see Materialized query table restrictions in the Db2 product documentation.
- You must be aware of
component restrictions. For more information, see fullselect in the Db2 product documentation.fullselect
- If IBM Knowledge
Catalog policy enforcement is enabled in
Data Virtualization, direct access to cache tables (MQT tables with names that start with
in theDV*
schema) is denied to all users.CACHESYS