# Oltp Vs Olap


![left](./student-guide/diagram/31-OLTP-OLAP-01-01.png)

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OLTP vs OLAP
Why is there a need for a HTAP database? Let's take a look at the traditional OLTP and OLAP services combined solution. On the far left of the figure is the OLTP service database, which supports row store. After the data is written to the OLTP business database, it will be extracted into the OLAP database (data warehouse or data lake) by ETL components to support Analyze the business. Later, the data may also be processed and extracted from the OLAP database back to other business scenario such as OLTP business databases or data marts, which will not be expanded here.

From the description just now, it's easy to see the problem with the two-point traditional solution:
1. ETL extraction has a considerable latency and cannot be fact-analyzed, for example, T+1, T+2, etc.
2. With multiple replica data, it's becoming increasingly difficult to maintain.