Feature extraction from relational database

In order to build a classifier, I need to extract a few features from the data stored on a MySQL database. I need to join multiple tables and it is taking a lot of time. I have joined 2 tables at one time and have got results in multiple cases. I need to combine them. Writing a script will be the best option? How do people extract features from large relational databases? Am I missing something?

Thanks.

Topic feature-extraction databases

Category Data Science

1
answered at

There are two end of the spectrum:

  1. Write a SQL query that creates a single materialized views that formatted in such a way that it is ready for machine learning.

  2. Write several SQL queries that fetch all possibly relevant data from the database. Then munge them in another system to create a table ready for machine learning.

It is often times the combination of those of two strategies.

The exact strategy depends on SQL query writing ability, size of the data, size of machine executing the database query, and ability to munge the data outside of SQL.

From personal experience, prioritize whatever works to get the job done or optimizing the workflow.

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