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During stats annotation column stats are updated based on ratio of change in number of rows. This heuristics can be improved by analyzing the filter expression and updating the column stats accordingly. For example: When filter expression is an equality to literal then NDV can be set to 1 directly. If the expression is an equality to column projection then min NDVs of the columns participating in expression can be taken.
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During stats annotation column stats are updated based on ratio of change in number of rows. This heuristics can be improved by analyzing the filter expression and updating the column stats accordingly. For example: When filter expression is an equality to literal then NDV can be set to 1 directly. If the expression is an equality to column projection then min NDVs of the columns participating in expression can be taken.
Sub-task
Major
Prasanth Jayachandran