Hello, I didn't quite get the concept of dimension...
# generalj
Jinal Panchal
05/06/2022, 12:04 PMHello, I didn't quite get the concept of dimension columns in Pinot.
If we have datatypes well-defined for the columns, then what's the significance of specifying Pinot field specification, like metricsField, dimensionFields, etc?
m
Mayank
05/06/2022, 2:32 PM
Metrics are things you count/sum/avg/etc. Dimensions are ones you slice/dice (filter/group) by.
Mayank
05/06/2022, 2:34 PM
While that is the idea, pinot does not enforce these as strict rules. Think of these as hints to pinot to do internal optimizations (for example, metrics by end up being stored without a dictionary, may have a different default null value, etc)
n
Neha Pawar
05/12/2022, 7:57 PM
just wanted to add here, these become more relevant when you do segment merge and rollups. Pinot will use dimensions + time to identify records to merge/rollup against
j
Jackie
05/12/2022, 8:06 PMAnother example would be for metrics aggregation, where we use dimensions and time as the key, and automatically aggregate values for the metrics
m
Mayank
05/12/2022, 8:06 PM
Yeah, I think we should document this 🙂