cartodb-postgresql/doc/CartoDB-user-table.md

A "cartodb" user table is a table with a well-known set of fields and a well-known set of triggers attached on.

The fields are:

• cartodb_id, a numerical primary key of serial type
• created_at, timestamp with timezone not null default now()
• updated_at, timestamp with timezone not null default now()
• the_geom, geometry, GiST indexed, constrained (see below)
• the_geom_webmercator, geometry, GiST indexed, constrained (see below)

The values of "the_geom" and "the_geom_webmercator" must match these constraints:

• Only POINT, MULTILINE, MULTIPOLYGON types ? Maybe UNCONSTRAINED
• Only 2 dimensions ? Maybe UNCONSTRAINED
• SRID=4326 for the_geom and SRID=3857 for the_geom_webmercator

The triggers are:

• track_updates after modifying statement updates cdb_tablemetadata
• test_quota before changing statement to forbid if overquota
• test_quota_per_row before changing row to forbod if overquota (checked on a probabilistic basis)
• update_the_geom_webmercator before insert or update row to maintain the_geom_webmercator
• update_updated_at_trigger before update row to maintain updated_at

Some conversions will be attempted to perform upon cartodbfication when certain fields appear:

• cartodb_id: If found type TEXT will be attempted to cast
• created_at: If found type TEXT will be attempted to cast
• updated_at: If found type TEXT will be attempted to cast