2.15 APPROX_FOR_COUNT_DISTINCT
APPROX_FOR_COUNT_DISTINCT
automatically replaces COUNT (DISTINCT expr)
queries with APPROX_COUNT_DISTINCT
queries.
Property | Description |
---|---|
Parameter type |
Boolean |
Default value |
|
Modifiable |
|
Modifiable in a PDB |
Yes |
Range of values |
|
Basic |
No |
Oracle RAC |
Different instances can use different values. |
Query results for APPROX_COUNT_DISTINCT
queries are returned faster than the equivalent COUNT (DISTINCT expr)
queries. APPROX_COUNT_DISTINCT
queries are useful for situations where a tolerable amount of error is acceptable in order to obtain faster query results than with a COUNT (DISTINCT expr)
query.
See Also: