Improving Column Compression

If you see slow performance or a large storage footprint with your FLOAT data, evaluate the data and your business needs to see if it can be contained in a NUMERIC column with a precision of 18 digits or less. Converting a FLOAT column to a NUMERIC column can improve data compression, reduce the on-disk size of your database, and improve performance of queries on that column.

When you define a NUMERIC data type, you specify the precision and the scale; NUMERIC data are exact representations of data. FLOAT data types represent variable precision and approximate values; they take up more space in the database.

Converting FLOAT columns to NUMERIC columns is most effective when:

If you try to load a value into a NUMERIC column that exceeds the specified precision, Vertica returns an error and does not load the data. If you assign a value with more decimal digits than the specified scale, the value is rounded to match the specified scale and stored in that column.

See Also

Numeric Data Types