[SOL-55] Filter on DOUBLE columns Created: 08.02.2014  Updated: 07.04.2020

Status: Published
Project: Solution Center
Component/s: EXASolution
Affects Version/s: EXASOL 6.0.0, Exasol 6.1.0, Exasol 6.2.0
Fix Version/s: None

Type: Explanation
Reporter: Captain EXASOL Assignee: Captain EXASOL
Labels: Filter

Issue Links:
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Solution:

Background

Filter on DOUBLE columns returns unexpected results. 

The DOUBLE values you see in EXAplus may differ from the actual database values due to the JDBC double handling and rendering.

Explanation

As the DOUBLE data type is only an approximative numeric type, filters on DOUBLE columns may return unexpected results, due to the approximative nature of this data type.

The datatype DOUBLE in the Exasol DB (including 6.x) is defined as an 64-Bit floating point value which represents values with a combination of an exponent and a fraction in binary form. This means that not every existing (numeric) value can be exactly represented by this type.

We recommend to filter only on DECIMAL columns to avoid described problems.

Additional References

The actual value range of this type can be seen in our documentation:

https://docs.exasol.com/sql_references/data_types/datatypedetails.htm

Category 1: SQL - Data types
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