1.12 APPROX_FOR_PERCENTILE

APPROX_FOR_PERCENTILE converts exact percentile functions to their approximate percentile function counterparts.

Property Description

Parameter type

String

Syntax

APPROX_FOR_PERCENTILE = { NONE | PERCENTILE_CONT | PERCENTILE_CONT DETERMINISTIC | PERCENTILE_DISC | PERCENTILE_DISC DETERMINISTIC | ALL | ALL DETERMINISTIC }

Default value

none

Modifiable

ALTER SESSION, ALTER SYSTEM

Modifiable in a PDB

Yes

Basic

No

Oracle RAC

Different instances can use different values.

Approximate percentile function queries are faster than their exact percentile function query counterparts, so they can be useful in situations where a tolerable amount of error is acceptable in order to obtain faster query results.

The values that can be set are:

  • NONE:

    No queries are converted. This is the default value.

  • PERCENTILE_CONT:

    Converts PERCENTILE_CONT queries to APPROX_PERCENTILE queries.

  • PERCENTILE_CONT DETERMINISTIC:

    Converts PERCENTILE_CONT queries to APPROX_PERCENTILE DETERMINSTIC queries.

  • PERCENTILE_DISC:

    Converts PERCENTILE_DISC queries to APPROX_PERCENTILE queries.

  • PERCENTILE DISC DETERMINISTIC:

    Converts PERCENTILE_DISC queries to APPROX_PERCENTILE DETERMINISTIC queries.

  • ALL:

    Converts both PERCENTILE_CONT queries and PERCENTILE_DISC queries to APPROX_PERCENTILE queries.

  • ALL DETERMINISTIC:

    Converts both PERCENTILE_CONT and PERCENTILE_DISC queries to APPROX_PERCENTILE DETERMINISTIC queries.

Note:

This initialization parameter is available starting with Oracle Database 12c Release 2 (12.2.0.1).

See Also: