Number Of Distinct Rows (NDV) is Calculated Incorrectly During Statistics Collection When Data Redaction is Used (Doc ID 2875553.1)

Last updated on JULY 20, 2024

Applies to:

Symptoms

Number of distinct rows (NDV) statistic for a specific column in a table keeps changing each time stats are gathered for that table. This happens in-spite of no modifications being done to the actual data.

For example:

After table statistics were collected, the NDV changed from a lower value of 30 -> very high value of 131191776. But next time the stats are gathered again, the value changes back to lower value, in this case - 30.

In this scenario, the 'TESTCOL' was actually being used to store identification related data, so ideally NDV should have been equal to number of rows in that table.
 

Changes

Cause

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