Blood counting machines aspirate a very small amount of the specimen through narrow tubing followed by an aperture and a laser flow cell. Laser eye sensors count the number of cells passing through the aperature, and can identify them; this is flow cytometry.
In computing, Extract, Transform and Load (ETL) refers to a process in database usage and especially in data warehousing that performs: Data extraction â extracts data from homogeneous or heterogeneous data sources.
The negative of this approach is it may take longer to get the data into the data warehouse as with the staging tables you have an extra step in the process, and you will need more disk space for the staging tables. More info: Difference between ETL and ELT.