# Comparison
# InfluxDB v2.0
InfluxDB (opens new window) is a popular time series database. InfluxQL is its query language, some of whose universal functions are related to data profiling. The comparison is shown below. Native means this function has been the native function of IoTDB and Built-in UDF means this function has been the built-in UDF of IoTDB.
| Data profiling functions of IoTDB-Quality | Univeral functions from InfluxQL |
|---|---|
| Native | COUNT() |
| Distinct | DISTINCT() |
| Integral | INTEGRAL() |
| Native | MEAN() |
| Median | MEDIAN() |
| Mode | MODE() |
| Spread | SPREAD() |
| Stddev | STDDEV() |
| Native | SUM() |
| Built-in UDF | BOTTOM() |
| Native | FIRST() |
| Native | LAST() |
| Native | MAX() |
| Native | MIN() |
| Percentile | PERCENTILE() |
| Sample | SAMPLE() |
| Built-in UDF | TOP() |
| Histogram | HISTOGRAM() |
| Mad | |
| Skew | SKEW() |
| TimeWeightedAVG | TIMEWEIGHTEDAVG() |
| SelfCorrelation | |
| CrossCorrelation |
Kapacitor offers UDF to realize user-defined anomaly detection. Python scripts can be applied to Kapacitor, and no native function for anomaly detection is offered in InfluxDB (opens new window).
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