The time range of stock data is approximate storage time, and stock data is data that already exists in the data warehouse or can be called historical data.

Stock data refers to the data held by the system before a certain time node. Flow data refers to the data that flows into and/or out of the system within a certain period of time. Among them, inflow or outflow data is called unilateral flow data, and inflow data plus outflow data is called bilateral flow data. Incremental data refers to the change of stock data in the system within a certain period of time. The relationship between them can be expressed by the following formula: incremental data = inflow data-outflow data.