TablesA database is the logical container of the relations. A relation is the relational object making the data accessible. The first kind of relation we'll take a look is the table.
This is the fundamental storage unit for the data. PostgreSQL implements various kind of tables having the full support, a partial implementation or no support at all for the durability.
The table creation is performed using the standard SQL command CREATE TABLE.
The PostgreSQL implementation does not guarantee the data is stored in a particular order. This is a straight MVCC consequence Take a look to 5.7 for more information.
The PostgreSQL implementation is rather confusing as the unique constraints aren't globally enforced on the inheritance tree and this prevents the foreign key to refer inherited tables. This limitation makes the table partitioning tricky.