Introduction to extraction, conversion and loading (vi) delivery of data to the presentation layer (to be continued)

The main task of ETL system is to pass dimension table and fact table in the commit phase.

The delivery subsystem is the backbone subsystem in the ETL architecture. Dimension tables are the heart of the Data Warehouse, and they provide the context for the fact table.

The dimension table is the entry into the fact table.

subsystem 9--slow Change dimension Manager

One of the most important elements in ETL is the implementation of slowly changing dimension (SCD) logic.

When the data warehouse learns that an existing row in a dimension has changed, there are three basic SCD responses-type 1 overlay, type 2 Add new row, and type 3 to add a new column. SCD uses these three methods or its hybrid approach to systematically process time-varying problems in dimensions.

subsystem 10--Surrogate Key generator

The surrogate key generator should generate surrogate keys independently for each dimension and should be independent of the DB instance and be able to support distributed clients.

The purpose of the Surrogate key generator is to generate a key that has no meaning, usually an integer, as the primary key for a dimension row.

The practice of creating surrogate keys from database triggers is common, but it can lead to performance bottlenecks.

Subsystem 11--Hierarchy Manager

Dimension attributes typically have multiple, simultaneous, embedded hierarchies. These diverse hierarchies generally coexist in the same dimension as dimension attributes. The only requirement is that each attribute only takes a single value when it appears in the primary key of the dimension.

The so-called hierarchy is unclear!

subsystem 12--dedicated Dimension Manager

Subsystem 13--fact Table builder

subsystem 14--Proxy key pipeline

subsystem 15--Multi-valued dimension bridge table Builder

subsystem 16--delayed arrival Data Processor

17--Dimension Management System of Subsystem

Subsystem 18--fact-providing system

subsystem 19--Aggregation Builder

subsystem 20--olap Cube Builder

subsystem 21--Data Propagation Manager

Introduction to extraction, conversion and loading (vi) delivery of data to the presentation layer (to be continued)