Frequently asked question
How does the Oracle optimizer derive an execution plan for a view containing an St_Geometry attribute?
Answer
An Oracle view's execution plan, when the view references a table containing an St_Geometry attribute with a spatial index, is derived in the same manner as an execution plan for a SQL statement executed directly against the table itself.The view is decomposed to the table objects it references by the optimizer. When the view contains an operator that references an St_Geometry attribute, the optimizer delegates the heuristics for calculating the queries cost to the st_domain_stats type.
The st_domain_stats type uses the statistics on the table the view references to calculate selectivity and cost. The statistics are maintained in the st_geometry_index table.
Article ID:000009600
Software:
- Legacy Products
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