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database_datawarehouse_datalake.qmd
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---
title: "Data['Base', 'Warehouse', 'Lake']"
format: html
---
## Conversation with Mike 8/24/22
Database schemas depend on the purpose
- Star and Snowflake is more useful for read purposes
- their nature is longer and wider tables. This is because there should be as little joining as possible
- T-SQL (OLTP AdventurWorks 2008 Schema) is more useful for write purposes
- Example of an advantageous time to use this is ___________
<br>
Star and Snowflake schemas differ by dimentionality
- If the Fact tables(s?) has dimentional tables and the dimentional tables do not have dimentional tables, it is a Star schema
- If the Fact tables(s?) has dimentional tables and the dimentional tables have dimentional tables, it is a Snowflake schema
<br>
How are databases connected in data warehouses? Can you query a data warehouse? (Can multiple databases be connected in the same query?)
- The Fact table is the most granular table of the database. It can/should be defined as something; like "For each student, semester, course, section, there is one grade, there is one _____"
- this is a many-to-one mostly
- the exception is survey data when one student can take many surveys
What about for each student there is one pell grant/scholarship and you don't need all the granularity
OLTP and OLAP: The two terms look similar but refer to different kinds of systems. Online transaction processing (OLTP) captures, stores, and processes data from transactions in real time. Online analytical processing (OLAP) uses complex queries to analyze aggregated historical data from OLTP systems.
Links found:
- https://github.com/orgs/microsoft/repositories
- https://github.com/microsoft/sql-server-samples
- https://github.com/microsoft/mssql-docker
- https://github.com/microsoft/sql-server-samples/tree/master/samples/databases
- https://www.microsoft.com/en-us/sql-server/developer-get-started/python/windows
- https://github.com/mkleehammer/pyodbc
- https://docs.microsoft.com/en-us/sql/sql-server/?redirectedfrom=MSDN&view=sql-server-ver16