Aggregate Functions
HoraeDB SQL is implemented with DataFusion, Here is the list of aggregate functions. See more detail, Refer to Datafusion
General
| Function | Description |
|---|
| min | Returns the minimum value in a numerical column |
| max | Returns the maximum value in a numerical column |
| count | Returns the number of rows |
| avg | Returns the average of a numerical column |
| sum | Sums a numerical column |
| array_agg | Puts values into an array |
Statistical
| Function | Description |
|---|
| var / var_samp | Returns the variance of a given column |
| var_pop | Returns the population variance of a given column |
| stddev / stddev_samp | Returns the standard deviation of a given column |
| stddev_pop | Returns the population standard deviation of a given column |
| covar / covar_samp | Returns the covariance of a given column |
| covar_pop | Returns the population covariance of a given column |
| corr | Returns the correlation coefficient of a given column |
Approximate
| Function | Description |
|---|
| approx_distinct | Returns the approximate number (HyperLogLog) of distinct input values |
| approx_median | Returns the approximate median of input values. It is an alias of approx_percentile_cont(x, 0.5). |
| approx_percentile_cont | Returns the approximate percentile (TDigest) of input values, where p is a float64 between 0 and 1 (inclusive). It supports raw data as input and build Tdigest sketches during query time, and is approximately equal to approx_percentile_cont_with_weight(x, 1, p). |
| approx_percentile_cont_with_weight | Returns the approximate percentile (TDigest) of input values with weight, where w is weight column expression and p is a float64 between 0 and 1 (inclusive). It supports raw data as input or pre-aggregated TDigest sketches, then builds or merges Tdigest sketches during query time. TDigest sketches are a list of centroid (x, w), where x stands for mean and w stands for weight. |