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Big Data Analytics

Star Transformation Restrictions

Star transformation is not supported for tables with any of the following

■ Queries with a table hint that is incompatible with a bitmap access path
■ Queries that contain bind variables
■ Tables with too few bitmap indexes. There must be a bitmap index on a fact table
column for the optimizer to generate a subquery for it.
■ Remote fact tables. However, remote dimension tables are allowed in the
subqueries that are generated.
■ Anti-joined tables
■ Tables that are already used as a dimension table in a subquery
■ Tables that are really unmerged views, which are not view partitions
The star transformation may not be chosen by the optimizer for the following cases:
■ Tables that have a good single-table access path
■ Tables that are too small for the transformation to be worthwhile
In addition, temporary tables will not be used by star transformation under the
following conditions:
■ The database is in read-only mode
■ The star query is part of a transaction that is in serializable mode

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