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Returns the common (base 10) logarithm of a numerical expression, or the logarithm to an arbitrary base if specified as the first argument. The value for which log is computed needs to be larger than 0, otherwise an error is returned. If a base is provided, it also needs to be larger than 0 and not equal to 1. You can use the function LN to compute the natural logarithm (base e). Alias: LOG10 (does not support a custom base argument)

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Syntax

LOG([<base>,] <value>);

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Parameters

ParameterDescriptionSupported input types
<base>Optional. The base for the logarithm. The default base is 10.DOUBLE PRECISION
<value>The value for which to compute the logarithm.DOUBLE PRECISION

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Return Type

DOUBLE PRECISION

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Example

The following example returns the logarithm of 64.0 to base 2: 
SELECT LOG(2, 64.0);
log double
6

Rows: 1Execution time: 5.31ms

The following example returns the logarithm of 100.0 to the default base 10: 
SELECT LOG(100.0), LOG10(100.0);
log doublelog10 double
22

Rows: 1Execution time: 5.68ms

The logarithm can only be computed for values that are larger than 0. All the following functions return an error: 
SELECT LOG(0.0);
-- SELECT LOG(-1.0);
-- SELECT LOG('-Inf');
| | | |

Rows: 0Execution time: 0.69ms

When a base is provided, it needs to be positive and not equal to zero. All the following functions return an error: 
SELECT LOG(0.0, 10.0);
-- SELECT LOG(-1.0, 10.0);
-- SELECT LOG(1.0, 10.0);
-- SELECT LOG('-Inf', 10.0);
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Rows: 0Execution time: 0.68ms