sql files for describing the database tables.
userregistry.sql contains all the fields that users have zero or one of, which include their profile page information.
causeskillindex describe two seperate tables, but virtually identical tables, one for causes and one for skills. the predifined causes and skills that users can add to their profiles and to activity postings. These definition rows are called "items." Since people have preferred names for similar causes and skills, the index contains an array of possible names the user can select for the same cause or skills. All causes and skills added to profiles and postings must use a name in the array in the index. The causes and skills also have an ID number, which works like the Dewey Decimal System, where a range of numbers represent a distinct category of causes and skills. This allows querying using < and > operators in the WHERE clause for finding items in a specific category.
causesandskill describes two nearly identical tables for causes and skills. These tables contain all items added to user's profiles. The username column references a username from the userregistry table, and the causeid or skillid columns reference the itemid from their respective dictionary table described by causeskillindex.sql. Users select a name from an array defined in the dictionary, and can submit a description for their experience with the specific cause or skill.
redis creates a table in postgres that does not store any data in postgres. The data is stored in Redis, an in memory key-value store, but can be queried with SQL and joined with postgres tables. This tables takes advantage of the Redis foreign data wrapper for Postgres.
###Why the '~'?
emacs makes them during autosaving of buffers.