When developing for WordPress and WooCommerce, it's important to consider the nature and permanence of your data. This will help you decide the best way to store it. Here's a quick primer:
If the data may not always be present (i.e., it expires), use a [transient](https://developer.wordpress.org/apis/handbook/transients/). Transients are a simple and standardized way of storing cached data in the database temporarily by giving it a custom name and a timeframe after which it will expire and be deleted.
If the data is persistent but not always present, consider using the [WP Cache](https://developer.wordpress.org/reference/classes/wp_object_cache/). The WP Cache functions allow you to cache data that is computationally expensive to regenerate, such as complex query results.
If the data is persistent and always present, consider the [wp_options table](https://developer.wordpress.org/apis/handbook/options/). The Options API is a simple and standardized way of storing data in the wp_options table in the WordPress database.
If the data type is an entity with n units, consider a [post type](https://developer.wordpress.org/post_type/). Post types are "types" of content that are stored in the same way, but are easy to distinguish in the code and UI.
If the data is a means of sorting/categorizing an entity, consider a [taxonomy](https://developer.wordpress.org/taxonomy/). Taxonomies are a way of grouping things together.
Logs should be written to a file using the [WC_Logger](https://woocommerce.com/wc-apidocs/class-WC_Logger.html) class. This is a simple and standardized way of recording events and errors for debugging purposes.
