FLOATING_POINT_ACCUMULATOR Option

1, 2, 3

2

Option can be set at the database (PUBLIC) or user level. At the database level, the value becomes the default for any new user, but has no impact on existing users. At the user level, overrides the PUBLIC value for that user only. No system privilege is required to set option for self. System privilege is required to set at database level or at user level for any user other than self.

Requires the SET ANY PUBLIC OPTION system privilege to set this option. Can be set temporary for an individual connection or for the PUBLIC role. Takes effect immediately.

Setting 1 (fast accumulator) is faster and uses less space for floats and doubles than setting 2. This setting uses a single double precision variable to add double and float numbers, and is subject to the known accuracy limitations of such an approach.

Setting 2 (default) (medium accumulator) uses multiple double precision variables to accumulate floats and doubles. It is very accurate for addends in the range of magnitudes 1e-20 to 1e20. While it loses some accuracy outside of this range, it is still accurate enough for most applications. Setting 2 allows the optimizer to choose hash for faster performance more easily than setting 3.

Setting 3 (large accumulator) is highly accurate for all floats and doubles, but its size often precludes the use of hash optimization, which will be a performance limitation for most applications.